Commit 60071659 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Boqun Feng

doc: Add EARLY flag to early-parsed kernel boot parameters

Kernel boot parameters declared with early_param() are parsed before
embedded parameters are extracted from initrd, and early_param()
parameters are not helpful when embedded in initrd.  Therefore,
mark early_param() kernel boot parameters with "EARLY" in
kernel-parameters.txt.

The following early_param() calls declare kernel boot parameters that
are undocumented:

early_param("atmel.pm_modes", at91_pm_modes_select);
early_param("mem_fclk_21285", early_fclk);
early_param("ecc", early_ecc);
early_param("cachepolicy", early_cachepolicy);
early_param("nodebugmon", early_debug_disable);
early_param("kfence.sample_interval", parse_kfence_early_init);
early_param("additional_cpus", setup_additional_cpus);
early_param("stram_pool", atari_stram_setup);
early_param("disable_octeon_edac", disable_octeon_edac);
early_param("rd_start", rd_start_early);
early_param("rd_size", rd_size_early);
early_param("coherentio", setcoherentio);
early_param("nocoherentio", setnocoherentio);
early_param("fadump", early_fadump_param);
early_param("fadump_reserve_mem", early_fadump_reserve_mem);
early_param("no_stf_barrier", handle_no_stf_barrier);
early_param("no_rfi_flush", handle_no_rfi_flush);
early_param("smt-enabled", early_smt_enabled);
early_param("ppc_pci_reset_phbs", pci_reset_phbs_setup);
early_param("ps3fb", early_parse_ps3fb);
early_param("ps3flash", early_parse_ps3flash);
early_param("novx", disable_vector_extension);
early_param("nobp", nobp_setup_early);
early_param("nospec", nospec_setup_early);
early_param("possible_cpus", _setup_possible_cpus);
early_param("stp", early_parse_stp);
early_param("nopfault", nopfault);
early_param("nmi_mode", nmi_mode_setup);
early_param("sh_mv", early_parse_mv);
early_param("pmb", early_pmb);
early_param("hvirq", early_hvirq_major);
early_param("cfi", cfi_parse_cmdline);
early_param("disableapic", setup_disableapic);
early_param("noapictimer", parse_disable_apic_timer);
early_param("disable_cpu_apicid", apic_set_disabled_cpu_apicid);
early_param("uv_memblksize", parse_mem_block_size);
early_param("retbleed", retbleed_parse_cmdline);
early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
early_param("update_mptable", update_mptable_setup);
early_param("alloc_mptable", parse_alloc_mptable_opt);
early_param("possible_cpus", _setup_possible_cpus);
early_param("lsmsi", early_parse_ls_scfg_msi);
early_param("nokgdbroundup", opt_nokgdbroundup);
early_param("kgdbcon", opt_kgdb_con);
early_param("kasan", early_kasan_flag);
early_param("kasan.mode", early_kasan_mode);
early_param("kasan.vmalloc", early_kasan_flag_vmalloc);
early_param("kasan.page_alloc.sample", early_kasan_flag_page_alloc_sample);
early_param("kasan.page_alloc.sample.order", early_kasan_flag_page_alloc_sample_order);
early_param("kasan.fault", early_kasan_fault);
early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
early_param("kasan.stack_ring_size", early_kasan_flag_stack_ring_size);
early_param("accept_memory", accept_memory_parse);
early_param("page_table_check", early_page_table_check_param);
sh_early_platform_init("earlytimer", &sh_cmt_device_driver);
early_param_on_off("gbpages", "nogbpages", direct_gbpages, CONFIG_X86_DIRECT_GBPAGES);

These are not necessarily bugs, given that some kernel boot parameters
are intended for deep debugging rather than general use.

This work does not cover all of the kernel boot parameters declared using
cmdline_find_option() and cmdline_find_option_bool().  If these are in
fact guaranteed to be early (which appears to be the case), they can be
added in a later version of this patch.
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Petr Malat <oss@malat.biz>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: <linux-doc@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: default avatarBoqun Feng <boqun.feng@gmail.com>
parent 739337d4
...@@ -108,6 +108,7 @@ is applicable:: ...@@ -108,6 +108,7 @@ is applicable::
CMA Contiguous Memory Area support is enabled. CMA Contiguous Memory Area support is enabled.
DRM Direct Rendering Management support is enabled. DRM Direct Rendering Management support is enabled.
DYNAMIC_DEBUG Build in debug messages and enable them at runtime DYNAMIC_DEBUG Build in debug messages and enable them at runtime
EARLY Parameter processed too early to be embedded in initrd.
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
EFI EFI Partitioning (GPT) is enabled EFI EFI Partitioning (GPT) is enabled
EVM Extended Verification Module EVM Extended Verification Module
......
...@@ -9,7 +9,7 @@ ...@@ -9,7 +9,7 @@
accept_memory=eager can be used to accept all memory accept_memory=eager can be used to accept all memory
at once during boot. at once during boot.
acpi= [HW,ACPI,X86,ARM64,RISCV64] acpi= [HW,ACPI,X86,ARM64,RISCV64,EARLY]
Advanced Configuration and Power Interface Advanced Configuration and Power Interface
Format: { force | on | off | strict | noirq | rsdt | Format: { force | on | off | strict | noirq | rsdt |
copy_dsdt } copy_dsdt }
...@@ -26,7 +26,7 @@ ...@@ -26,7 +26,7 @@
See also Documentation/power/runtime_pm.rst, pci=noacpi See also Documentation/power/runtime_pm.rst, pci=noacpi
acpi_apic_instance= [ACPI, IOAPIC] acpi_apic_instance= [ACPI,IOAPIC,EARLY]
Format: <int> Format: <int>
2: use 2nd APIC table, if available 2: use 2nd APIC table, if available
1,0: use 1st APIC table 1,0: use 1st APIC table
...@@ -41,7 +41,7 @@ ...@@ -41,7 +41,7 @@
If set to native, use the device's native backlight mode. If set to native, use the device's native backlight mode.
If set to none, disable the ACPI backlight interface. If set to none, disable the ACPI backlight interface.
acpi_force_32bit_fadt_addr acpi_force_32bit_fadt_addr [ACPI,EARLY]
force FADT to use 32 bit addresses rather than the force FADT to use 32 bit addresses rather than the
64 bit X_* addresses. Some firmware have broken 64 64 bit X_* addresses. Some firmware have broken 64
bit addresses for force ACPI ignore these and use bit addresses for force ACPI ignore these and use
...@@ -97,7 +97,7 @@ ...@@ -97,7 +97,7 @@
no: ACPI OperationRegions are not marked as reserved, no: ACPI OperationRegions are not marked as reserved,
no further checks are performed. no further checks are performed.
acpi_force_table_verification [HW,ACPI] acpi_force_table_verification [HW,ACPI,EARLY]
Enable table checksum verification during early stage. Enable table checksum verification during early stage.
By default, this is disabled due to x86 early mapping By default, this is disabled due to x86 early mapping
size limitation. size limitation.
...@@ -137,7 +137,7 @@ ...@@ -137,7 +137,7 @@
acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump
kernels. kernels.
acpi_no_static_ssdt [HW,ACPI] acpi_no_static_ssdt [HW,ACPI,EARLY]
Disable installation of static SSDTs at early boot time Disable installation of static SSDTs at early boot time
By default, SSDTs contained in the RSDT/XSDT will be By default, SSDTs contained in the RSDT/XSDT will be
installed automatically and they will appear under installed automatically and they will appear under
...@@ -151,7 +151,7 @@ ...@@ -151,7 +151,7 @@
Ignore the ACPI-based watchdog interface (WDAT) and let Ignore the ACPI-based watchdog interface (WDAT) and let
a native driver control the watchdog device instead. a native driver control the watchdog device instead.
acpi_rsdp= [ACPI,EFI,KEXEC] acpi_rsdp= [ACPI,EFI,KEXEC,EARLY]
Pass the RSDP address to the kernel, mostly used Pass the RSDP address to the kernel, mostly used
on machines running EFI runtime service to boot the on machines running EFI runtime service to boot the
second kernel for kdump. second kernel for kdump.
...@@ -228,10 +228,10 @@ ...@@ -228,10 +228,10 @@
to assume that this machine's pmtimer latches its value to assume that this machine's pmtimer latches its value
and always returns good values. and always returns good values.
acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode acpi_sci= [HW,ACPI,EARLY] ACPI System Control Interrupt trigger mode
Format: { level | edge | high | low } Format: { level | edge | high | low }
acpi_skip_timer_override [HW,ACPI] acpi_skip_timer_override [HW,ACPI,EARLY]
Recognize and ignore IRQ0/pin2 Interrupt Override. Recognize and ignore IRQ0/pin2 Interrupt Override.
For broken nForce2 BIOS resulting in XT-PIC timer. For broken nForce2 BIOS resulting in XT-PIC timer.
...@@ -266,11 +266,11 @@ ...@@ -266,11 +266,11 @@
behave incorrectly in some ways with respect to system behave incorrectly in some ways with respect to system
suspend and resume to be ignored (use wisely). suspend and resume to be ignored (use wisely).
acpi_use_timer_override [HW,ACPI] acpi_use_timer_override [HW,ACPI,EARLY]
Use timer override. For some broken Nvidia NF5 boards Use timer override. For some broken Nvidia NF5 boards
that require a timer override, but don't have HPET that require a timer override, but don't have HPET
add_efi_memmap [EFI; X86] Include EFI memory map in add_efi_memmap [EFI,X86,EARLY] Include EFI memory map in
kernel's map of available physical RAM. kernel's map of available physical RAM.
agp= [AGP] agp= [AGP]
...@@ -307,7 +307,7 @@ ...@@ -307,7 +307,7 @@
do not want to use tracing_snapshot_alloc() as it needs do not want to use tracing_snapshot_alloc() as it needs
to be done where GFP_KERNEL allocations are allowed. to be done where GFP_KERNEL allocations are allowed.
allow_mismatched_32bit_el0 [ARM64] allow_mismatched_32bit_el0 [ARM64,EARLY]
Allow execve() of 32-bit applications and setting of the Allow execve() of 32-bit applications and setting of the
PER_LINUX32 personality on systems where only a strict PER_LINUX32 personality on systems where only a strict
subset of the CPUs support 32-bit EL0. When this subset of the CPUs support 32-bit EL0. When this
...@@ -351,7 +351,7 @@ ...@@ -351,7 +351,7 @@
This mode requires kvm-amd.avic=1. This mode requires kvm-amd.avic=1.
(Default when IOMMU HW support is present.) (Default when IOMMU HW support is present.)
amd_pstate= [X86] amd_pstate= [X86,EARLY]
disable disable
Do not enable amd_pstate as the default Do not enable amd_pstate as the default
scaling driver for the supported processors scaling driver for the supported processors
...@@ -391,7 +391,7 @@ ...@@ -391,7 +391,7 @@
not play well with APC CPU idle - disable it if you have not play well with APC CPU idle - disable it if you have
APC and your system crashes randomly. APC and your system crashes randomly.
apic= [APIC,X86] Advanced Programmable Interrupt Controller apic= [APIC,X86,EARLY] Advanced Programmable Interrupt Controller
Change the output verbosity while booting Change the output verbosity while booting
Format: { quiet (default) | verbose | debug } Format: { quiet (default) | verbose | debug }
Change the amount of debugging information output Change the amount of debugging information output
...@@ -401,7 +401,7 @@ ...@@ -401,7 +401,7 @@
Format: apic=driver_name Format: apic=driver_name
Examples: apic=bigsmp Examples: apic=bigsmp
apic_extnmi= [APIC,X86] External NMI delivery setting apic_extnmi= [APIC,X86,EARLY] External NMI delivery setting
Format: { bsp (default) | all | none } Format: { bsp (default) | all | none }
bsp: External NMI is delivered only to CPU 0 bsp: External NMI is delivered only to CPU 0
all: External NMIs are broadcast to all CPUs as a all: External NMIs are broadcast to all CPUs as a
...@@ -508,21 +508,22 @@ ...@@ -508,21 +508,22 @@
bert_disable [ACPI] bert_disable [ACPI]
Disable BERT OS support on buggy BIOSes. Disable BERT OS support on buggy BIOSes.
bgrt_disable [ACPI][X86] bgrt_disable [ACPI,X86,EARLY]
Disable BGRT to avoid flickering OEM logo. Disable BGRT to avoid flickering OEM logo.
blkdevparts= Manual partition parsing of block device(s) for blkdevparts= Manual partition parsing of block device(s) for
embedded devices based on command line input. embedded devices based on command line input.
See Documentation/block/cmdline-partition.rst See Documentation/block/cmdline-partition.rst
boot_delay= Milliseconds to delay each printk during boot. boot_delay= [KNL,EARLY]
Milliseconds to delay each printk during boot.
Only works if CONFIG_BOOT_PRINTK_DELAY is enabled, Only works if CONFIG_BOOT_PRINTK_DELAY is enabled,
and you may also have to specify "lpj=". Boot_delay and you may also have to specify "lpj=". Boot_delay
values larger than 10 seconds (10000) are assumed values larger than 10 seconds (10000) are assumed
erroneous and ignored. erroneous and ignored.
Format: integer Format: integer
bootconfig [KNL] bootconfig [KNL,EARLY]
Extended command line options can be added to an initrd Extended command line options can be added to an initrd
and this will cause the kernel to look for it. and this will cause the kernel to look for it.
...@@ -557,7 +558,7 @@ ...@@ -557,7 +558,7 @@
trust validation. trust validation.
format: { id:<keyid> | builtin } format: { id:<keyid> | builtin }
cca= [MIPS] Override the kernel pages' cache coherency cca= [MIPS,EARLY] Override the kernel pages' cache coherency
algorithm. Accepted values range from 0 to 7 algorithm. Accepted values range from 0 to 7
inclusive. See arch/mips/include/asm/pgtable-bits.h inclusive. See arch/mips/include/asm/pgtable-bits.h
for platform specific values (SB1, Loongson3 and for platform specific values (SB1, Loongson3 and
...@@ -672,7 +673,7 @@ ...@@ -672,7 +673,7 @@
[X86-64] hpet,tsc [X86-64] hpet,tsc
clocksource.arm_arch_timer.evtstrm= clocksource.arm_arch_timer.evtstrm=
[ARM,ARM64] [ARM,ARM64,EARLY]
Format: <bool> Format: <bool>
Enable/disable the eventstream feature of the ARM Enable/disable the eventstream feature of the ARM
architected timer so that code using WFE-based polling architected timer so that code using WFE-based polling
...@@ -702,7 +703,7 @@ ...@@ -702,7 +703,7 @@
10 seconds when built into the kernel. 10 seconds when built into the kernel.
cma=nn[MG]@[start[MG][-end[MG]]] cma=nn[MG]@[start[MG][-end[MG]]]
[KNL,CMA] [KNL,CMA,EARLY]
Sets the size of kernel global memory area for Sets the size of kernel global memory area for
contiguous memory allocations and optionally the contiguous memory allocations and optionally the
placement constraint by the physical address range of placement constraint by the physical address range of
...@@ -711,7 +712,7 @@ ...@@ -711,7 +712,7 @@
kernel/dma/contiguous.c kernel/dma/contiguous.c
cma_pernuma=nn[MG] cma_pernuma=nn[MG]
[KNL,CMA] [KNL,CMA,EARLY]
Sets the size of kernel per-numa memory area for Sets the size of kernel per-numa memory area for
contiguous memory allocations. A value of 0 disables contiguous memory allocations. A value of 0 disables
per-numa CMA altogether. And If this option is not per-numa CMA altogether. And If this option is not
...@@ -722,7 +723,7 @@ ...@@ -722,7 +723,7 @@
they will fallback to the global default memory area. they will fallback to the global default memory area.
numa_cma=<node>:nn[MG][,<node>:nn[MG]] numa_cma=<node>:nn[MG][,<node>:nn[MG]]
[KNL,CMA] [KNL,CMA,EARLY]
Sets the size of kernel numa memory area for Sets the size of kernel numa memory area for
contiguous memory allocations. It will reserve CMA contiguous memory allocations. It will reserve CMA
area for the specified node. area for the specified node.
...@@ -739,7 +740,7 @@ ...@@ -739,7 +740,7 @@
a hypervisor. a hypervisor.
Default: yes Default: yes
coherent_pool=nn[KMG] [ARM,KNL] coherent_pool=nn[KMG] [ARM,KNL,EARLY]
Sets the size of memory pool for coherent, atomic dma Sets the size of memory pool for coherent, atomic dma
allocations, by default set to 256K. allocations, by default set to 256K.
...@@ -757,7 +758,7 @@ ...@@ -757,7 +758,7 @@
condev= [HW,S390] console device condev= [HW,S390] console device
conmode= conmode=
con3215_drop= [S390] 3215 console drop mode. con3215_drop= [S390,EARLY] 3215 console drop mode.
Format: y|n|Y|N|1|0 Format: y|n|Y|N|1|0
When set to true, drop data on the 3215 console when When set to true, drop data on the 3215 console when
the console buffer is full. In this case the the console buffer is full. In this case the
...@@ -863,7 +864,7 @@ ...@@ -863,7 +864,7 @@
kernel before the cpufreq driver probes. kernel before the cpufreq driver probes.
cpu_init_udelay=N cpu_init_udelay=N
[X86] Delay for N microsec between assert and de-assert [X86,EARLY] Delay for N microsec between assert and de-assert
of APIC INIT to start processors. This delay occurs of APIC INIT to start processors. This delay occurs
on every CPU online, such as boot, and resume from suspend. on every CPU online, such as boot, and resume from suspend.
Default: 10000 Default: 10000
...@@ -883,7 +884,7 @@ ...@@ -883,7 +884,7 @@
kernel more unstable. kernel more unstable.
crashkernel=size[KMG][@offset[KMG]] crashkernel=size[KMG][@offset[KMG]]
[KNL] Using kexec, Linux can switch to a 'crash kernel' [KNL,EARLY] Using kexec, Linux can switch to a 'crash kernel'
upon panic. This parameter reserves the physical upon panic. This parameter reserves the physical
memory region [offset, offset + size] for that kernel memory region [offset, offset + size] for that kernel
image. If '@offset' is omitted, then a suitable offset image. If '@offset' is omitted, then a suitable offset
...@@ -954,10 +955,10 @@ ...@@ -954,10 +955,10 @@
Format: <port#>,<type> Format: <port#>,<type>
See also Documentation/input/devices/joystick-parport.rst See also Documentation/input/devices/joystick-parport.rst
debug [KNL] Enable kernel debugging (events log level). debug [KNL,EARLY] Enable kernel debugging (events log level).
debug_boot_weak_hash debug_boot_weak_hash
[KNL] Enable printing [hashed] pointers early in the [KNL,EARLY] Enable printing [hashed] pointers early in the
boot sequence. If enabled, we use a weak hash instead boot sequence. If enabled, we use a weak hash instead
of siphash to hash pointers. Use this option if you are of siphash to hash pointers. Use this option if you are
seeing instances of '(___ptrval___)') and need to see a seeing instances of '(___ptrval___)') and need to see a
...@@ -974,10 +975,10 @@ ...@@ -974,10 +975,10 @@
will print _a_lot_ more information - normally only will print _a_lot_ more information - normally only
useful to lockdep developers. useful to lockdep developers.
debug_objects [KNL] Enable object debugging debug_objects [KNL,EARLY] Enable object debugging
debug_guardpage_minorder= debug_guardpage_minorder=
[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this [KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this
parameter allows control of the order of pages that will parameter allows control of the order of pages that will
be intentionally kept free (and hence protected) by the be intentionally kept free (and hence protected) by the
buddy allocator. Bigger value increase the probability buddy allocator. Bigger value increase the probability
...@@ -996,7 +997,7 @@ ...@@ -996,7 +997,7 @@
help tracking down these problems. help tracking down these problems.
debug_pagealloc= debug_pagealloc=
[KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter [KNL,EARLY] When CONFIG_DEBUG_PAGEALLOC is set, this parameter
enables the feature at boot time. By default, it is enables the feature at boot time. By default, it is
disabled and the system will work mostly the same as a disabled and the system will work mostly the same as a
kernel built without CONFIG_DEBUG_PAGEALLOC. kernel built without CONFIG_DEBUG_PAGEALLOC.
...@@ -1004,8 +1005,8 @@ ...@@ -1004,8 +1005,8 @@
useful to also enable the page_owner functionality. useful to also enable the page_owner functionality.
on: enable the feature on: enable the feature
debugfs= [KNL] This parameter enables what is exposed to userspace debugfs= [KNL,EARLY] This parameter enables what is exposed to
and debugfs internal clients. userspace and debugfs internal clients.
Format: { on, no-mount, off } Format: { on, no-mount, off }
on: All functions are enabled. on: All functions are enabled.
no-mount: no-mount:
...@@ -1084,7 +1085,7 @@ ...@@ -1084,7 +1085,7 @@
dhash_entries= [KNL] dhash_entries= [KNL]
Set number of hash buckets for dentry cache. Set number of hash buckets for dentry cache.
disable_1tb_segments [PPC] disable_1tb_segments [PPC,EARLY]
Disables the use of 1TB hash page table segments. This Disables the use of 1TB hash page table segments. This
causes the kernel to fall back to 256MB segments which causes the kernel to fall back to 256MB segments which
can be useful when debugging issues that require an SLB can be useful when debugging issues that require an SLB
...@@ -1093,7 +1094,7 @@ ...@@ -1093,7 +1094,7 @@
disable= [IPV6] disable= [IPV6]
See Documentation/networking/ipv6.rst. See Documentation/networking/ipv6.rst.
disable_radix [PPC] disable_radix [PPC,EARLY]
Disable RADIX MMU mode on POWER9 Disable RADIX MMU mode on POWER9
disable_tlbie [PPC] disable_tlbie [PPC]
...@@ -1109,25 +1110,25 @@ ...@@ -1109,25 +1110,25 @@
causing system reset or hang due to sending causing system reset or hang due to sending
INIT from AP to BSP. INIT from AP to BSP.
disable_ddw [PPC/PSERIES] disable_ddw [PPC/PSERIES,EARLY]
Disable Dynamic DMA Window support. Use this Disable Dynamic DMA Window support. Use this
to workaround buggy firmware. to workaround buggy firmware.
disable_ipv6= [IPV6] disable_ipv6= [IPV6]
See Documentation/networking/ipv6.rst. See Documentation/networking/ipv6.rst.
disable_mtrr_cleanup [X86] disable_mtrr_cleanup [X86,EARLY]
The kernel tries to adjust MTRR layout from continuous The kernel tries to adjust MTRR layout from continuous
to discrete, to make X server driver able to add WB to discrete, to make X server driver able to add WB
entry later. This parameter disables that. entry later. This parameter disables that.
disable_mtrr_trim [X86, Intel and AMD only] disable_mtrr_trim [X86, Intel and AMD only,EARLY]
By default the kernel will trim any uncacheable By default the kernel will trim any uncacheable
memory out of your available memory pool based on memory out of your available memory pool based on
MTRR settings. This parameter disables that behavior, MTRR settings. This parameter disables that behavior,
possibly causing your machine to run very slowly. possibly causing your machine to run very slowly.
disable_timer_pin_1 [X86] disable_timer_pin_1 [X86,EARLY]
Disable PIN 1 of APIC timer Disable PIN 1 of APIC timer
Can be useful to work around chipset bugs. Can be useful to work around chipset bugs.
...@@ -1177,7 +1178,7 @@ ...@@ -1177,7 +1178,7 @@
dscc4.setup= [NET] dscc4.setup= [NET]
dt_cpu_ftrs= [PPC] dt_cpu_ftrs= [PPC,EARLY]
Format: {"off" | "known"} Format: {"off" | "known"}
Control how the dt_cpu_ftrs device-tree binding is Control how the dt_cpu_ftrs device-tree binding is
used for CPU feature discovery and setup (if it used for CPU feature discovery and setup (if it
...@@ -1197,12 +1198,12 @@ ...@@ -1197,12 +1198,12 @@
Documentation/admin-guide/dynamic-debug-howto.rst Documentation/admin-guide/dynamic-debug-howto.rst
for details. for details.
early_ioremap_debug [KNL] early_ioremap_debug [KNL,EARLY]
Enable debug messages in early_ioremap support. This Enable debug messages in early_ioremap support. This
is useful for tracking down temporary early mappings is useful for tracking down temporary early mappings
which are not unmapped. which are not unmapped.
earlycon= [KNL] Output early console device and options. earlycon= [KNL,EARLY] Output early console device and options.
When used with no options, the early console is When used with no options, the early console is
determined by stdout-path property in device tree's determined by stdout-path property in device tree's
...@@ -1338,7 +1339,7 @@ ...@@ -1338,7 +1339,7 @@
address must be provided, and the serial port must address must be provided, and the serial port must
already be setup and configured. already be setup and configured.
earlyprintk= [X86,SH,ARM,M68k,S390] earlyprintk= [X86,SH,ARM,M68k,S390,UM,EARLY]
earlyprintk=vga earlyprintk=vga
earlyprintk=sclp earlyprintk=sclp
earlyprintk=xen earlyprintk=xen
...@@ -1396,7 +1397,7 @@ ...@@ -1396,7 +1397,7 @@
edd= [EDD] edd= [EDD]
Format: {"off" | "on" | "skip[mbr]"} Format: {"off" | "on" | "skip[mbr]"}
efi= [EFI] efi= [EFI,EARLY]
Format: { "debug", "disable_early_pci_dma", Format: { "debug", "disable_early_pci_dma",
"nochunk", "noruntime", "nosoftreserve", "nochunk", "noruntime", "nosoftreserve",
"novamap", "no_disable_early_pci_dma" } "novamap", "no_disable_early_pci_dma" }
...@@ -1417,13 +1418,13 @@ ...@@ -1417,13 +1418,13 @@
no_disable_early_pci_dma: Leave the busmaster bit set no_disable_early_pci_dma: Leave the busmaster bit set
on all PCI bridges while in the EFI boot stub on all PCI bridges while in the EFI boot stub
efi_no_storage_paranoia [EFI; X86] efi_no_storage_paranoia [EFI,X86,EARLY]
Using this parameter you can use more than 50% of Using this parameter you can use more than 50% of
your efi variable storage. Use this parameter only if your efi variable storage. Use this parameter only if
you are really sure that your UEFI does sane gc and you are really sure that your UEFI does sane gc and
fulfills the spec otherwise your board may brick. fulfills the spec otherwise your board may brick.
efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86] efi_fake_mem= nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI,X86,EARLY]
Add arbitrary attribute to specific memory range by Add arbitrary attribute to specific memory range by
updating original EFI memory map. updating original EFI memory map.
Region of memory which aa attribute is added to is Region of memory which aa attribute is added to is
...@@ -1454,7 +1455,7 @@ ...@@ -1454,7 +1455,7 @@
eisa_irq_edge= [PARISC,HW] eisa_irq_edge= [PARISC,HW]
See header of drivers/parisc/eisa.c. See header of drivers/parisc/eisa.c.
ekgdboc= [X86,KGDB] Allow early kernel console debugging ekgdboc= [X86,KGDB,EARLY] Allow early kernel console debugging
Format: ekgdboc=kbd Format: ekgdboc=kbd
This is designed to be used in conjunction with This is designed to be used in conjunction with
...@@ -1469,13 +1470,13 @@ ...@@ -1469,13 +1470,13 @@
See comment before function elanfreq_setup() in See comment before function elanfreq_setup() in
arch/x86/kernel/cpu/cpufreq/elanfreq.c. arch/x86/kernel/cpu/cpufreq/elanfreq.c.
elfcorehdr=[size[KMG]@]offset[KMG] [PPC,SH,X86,S390] elfcorehdr=[size[KMG]@]offset[KMG] [PPC,SH,X86,S390,EARLY]
Specifies physical address of start of kernel core Specifies physical address of start of kernel core
image elf header and optionally the size. Generally image elf header and optionally the size. Generally
kexec loader will pass this option to capture kernel. kexec loader will pass this option to capture kernel.
See Documentation/admin-guide/kdump/kdump.rst for details. See Documentation/admin-guide/kdump/kdump.rst for details.
enable_mtrr_cleanup [X86] enable_mtrr_cleanup [X86,EARLY]
The kernel tries to adjust MTRR layout from continuous The kernel tries to adjust MTRR layout from continuous
to discrete, to make X server driver able to add WB to discrete, to make X server driver able to add WB
entry later. This parameter enables that. entry later. This parameter enables that.
...@@ -1508,7 +1509,7 @@ ...@@ -1508,7 +1509,7 @@
Permit 'security.evm' to be updated regardless of Permit 'security.evm' to be updated regardless of
current integrity status. current integrity status.
early_page_ext [KNL] Enforces page_ext initialization to earlier early_page_ext [KNL,EARLY] Enforces page_ext initialization to earlier
stages so cover more early boot allocations. stages so cover more early boot allocations.
Please note that as side effect some optimizations Please note that as side effect some optimizations
might be disabled to achieve that (e.g. parallelized might be disabled to achieve that (e.g. parallelized
...@@ -1600,7 +1601,7 @@ ...@@ -1600,7 +1601,7 @@
can be changed at run time by the max_graph_depth file can be changed at run time by the max_graph_depth file
in the tracefs tracing directory. default: 0 (no limit) in the tracefs tracing directory. default: 0 (no limit)
fw_devlink= [KNL] Create device links between consumer and supplier fw_devlink= [KNL,EARLY] Create device links between consumer and supplier
devices by scanning the firmware to infer the devices by scanning the firmware to infer the
consumer/supplier relationships. This feature is consumer/supplier relationships. This feature is
especially useful when drivers are loaded as modules as especially useful when drivers are loaded as modules as
...@@ -1619,12 +1620,12 @@ ...@@ -1619,12 +1620,12 @@
rpm -- Like "on", but also use to order runtime PM. rpm -- Like "on", but also use to order runtime PM.
fw_devlink.strict=<bool> fw_devlink.strict=<bool>
[KNL] Treat all inferred dependencies as mandatory [KNL,EARLY] Treat all inferred dependencies as mandatory
dependencies. This only applies for fw_devlink=on|rpm. dependencies. This only applies for fw_devlink=on|rpm.
Format: <bool> Format: <bool>
fw_devlink.sync_state = fw_devlink.sync_state =
[KNL] When all devices that could probe have finished [KNL,EARLY] When all devices that could probe have finished
probing, this parameter controls what to do with probing, this parameter controls what to do with
devices that haven't yet received their sync_state() devices that haven't yet received their sync_state()
calls. calls.
...@@ -1645,12 +1646,12 @@ ...@@ -1645,12 +1646,12 @@
gamma= [HW,DRM] gamma= [HW,DRM]
gart_fix_e820= [X86-64] disable the fix e820 for K8 GART gart_fix_e820= [X86-64,EARLY] disable the fix e820 for K8 GART
Format: off | on Format: off | on
default: on default: on
gather_data_sampling= gather_data_sampling=
[X86,INTEL] Control the Gather Data Sampling (GDS) [X86,INTEL,EARLY] Control the Gather Data Sampling (GDS)
mitigation. mitigation.
Gather Data Sampling is a hardware vulnerability which Gather Data Sampling is a hardware vulnerability which
...@@ -1748,7 +1749,7 @@ ...@@ -1748,7 +1749,7 @@
(that will set all pages holding image data (that will set all pages holding image data
during restoration read-only). during restoration read-only).
highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact highmem=nn[KMG] [KNL,BOOT,EARLY] forces the highmem zone to have an exact
size of <nn>. This works even on boxes that have no size of <nn>. This works even on boxes that have no
highmem otherwise. This also works to reduce highmem highmem otherwise. This also works to reduce highmem
size on bigger boxes. size on bigger boxes.
...@@ -1759,7 +1760,7 @@ ...@@ -1759,7 +1760,7 @@
hlt [BUGS=ARM,SH] hlt [BUGS=ARM,SH]
hostname= [KNL] Set the hostname (aka UTS nodename). hostname= [KNL,EARLY] Set the hostname (aka UTS nodename).
Format: <string> Format: <string>
This allows setting the system's hostname during early This allows setting the system's hostname during early
startup. This sets the name returned by gethostname. startup. This sets the name returned by gethostname.
...@@ -1804,7 +1805,7 @@ ...@@ -1804,7 +1805,7 @@
Documentation/admin-guide/mm/hugetlbpage.rst. Documentation/admin-guide/mm/hugetlbpage.rst.
Format: size[KMG] Format: size[KMG]
hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation hugetlb_cma= [HW,CMA,EARLY] The size of a CMA area used for allocation
of gigantic hugepages. Or using node format, the size of gigantic hugepages. Or using node format, the size
of a CMA area per node can be specified. of a CMA area per node can be specified.
Format: nn[KMGTPE] or (node format) Format: nn[KMGTPE] or (node format)
...@@ -1850,9 +1851,10 @@ ...@@ -1850,9 +1851,10 @@
If specified, z/VM IUCV HVC accepts connections If specified, z/VM IUCV HVC accepts connections
from listed z/VM user IDs only. from listed z/VM user IDs only.
hv_nopvspin [X86,HYPER_V] Disables the paravirt spinlock optimizations hv_nopvspin [X86,HYPER_V,EARLY]
which allow the hypervisor to 'idle' the Disables the paravirt spinlock optimizations
guest on lock contention. which allow the hypervisor to 'idle' the guest
on lock contention.
i2c_bus= [HW] Override the default board specific I2C bus speed i2c_bus= [HW] Override the default board specific I2C bus speed
or register an additional I2C bus that is not or register an additional I2C bus that is not
...@@ -1917,7 +1919,7 @@ ...@@ -1917,7 +1919,7 @@
Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
idle= [X86] idle= [X86,EARLY]
Format: idle=poll, idle=halt, idle=nomwait Format: idle=poll, idle=halt, idle=nomwait
Poll forces a polling idle loop that can slightly Poll forces a polling idle loop that can slightly
improve the performance of waking up a idle CPU, but improve the performance of waking up a idle CPU, but
...@@ -1973,7 +1975,7 @@ ...@@ -1973,7 +1975,7 @@
mode generally follows that for the NaN encoding, mode generally follows that for the NaN encoding,
except where unsupported by hardware. except where unsupported by hardware.
ignore_loglevel [KNL] ignore_loglevel [KNL,EARLY]
Ignore loglevel setting - this will print /all/ Ignore loglevel setting - this will print /all/
kernel messages to the console. Useful for debugging. kernel messages to the console. Useful for debugging.
We also add it as printk module parameter, so users We also add it as printk module parameter, so users
...@@ -2091,21 +2093,21 @@ ...@@ -2091,21 +2093,21 @@
unpacking being completed before device_ and unpacking being completed before device_ and
late_ initcalls. late_ initcalls.
initrd= [BOOT] Specify the location of the initial ramdisk initrd= [BOOT,EARLY] Specify the location of the initial ramdisk
initrdmem= [KNL] Specify a physical address and size from which to initrdmem= [KNL,EARLY] Specify a physical address and size from which to
load the initrd. If an initrd is compiled in or load the initrd. If an initrd is compiled in or
specified in the bootparams, it takes priority over this specified in the bootparams, it takes priority over this
setting. setting.
Format: ss[KMG],nn[KMG] Format: ss[KMG],nn[KMG]
Default is 0, 0 Default is 0, 0
init_on_alloc= [MM] Fill newly allocated pages and heap objects with init_on_alloc= [MM,EARLY] Fill newly allocated pages and heap objects with
zeroes. zeroes.
Format: 0 | 1 Format: 0 | 1
Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON. Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON.
init_on_free= [MM] Fill freed pages and heap objects with zeroes. init_on_free= [MM,EARLY] Fill freed pages and heap objects with zeroes.
Format: 0 | 1 Format: 0 | 1
Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON.
...@@ -2161,7 +2163,7 @@ ...@@ -2161,7 +2163,7 @@
0 disables intel_idle and fall back on acpi_idle. 0 disables intel_idle and fall back on acpi_idle.
1 to 9 specify maximum depth of C-state. 1 to 9 specify maximum depth of C-state.
intel_pstate= [X86] intel_pstate= [X86,EARLY]
disable disable
Do not enable intel_pstate as the default Do not enable intel_pstate as the default
scaling driver for the supported processors scaling driver for the supported processors
...@@ -2205,7 +2207,7 @@ ...@@ -2205,7 +2207,7 @@
Allow per-logical-CPU P-State performance control limits using Allow per-logical-CPU P-State performance control limits using
cpufreq sysfs interface cpufreq sysfs interface
intremap= [X86-64, Intel-IOMMU] intremap= [X86-64,Intel-IOMMU,EARLY]
on enable Interrupt Remapping (default) on enable Interrupt Remapping (default)
off disable Interrupt Remapping off disable Interrupt Remapping
nosid disable Source ID checking nosid disable Source ID checking
...@@ -2217,7 +2219,7 @@ ...@@ -2217,7 +2219,7 @@
strict regions from userspace. strict regions from userspace.
relaxed relaxed
iommu= [X86] iommu= [X86,EARLY]
off off
force force
noforce noforce
...@@ -2232,7 +2234,7 @@ ...@@ -2232,7 +2234,7 @@
nobypass [PPC/POWERNV] nobypass [PPC/POWERNV]
Disable IOMMU bypass, using IOMMU for PCI devices. Disable IOMMU bypass, using IOMMU for PCI devices.
iommu.forcedac= [ARM64, X86] Control IOVA allocation for PCI devices. iommu.forcedac= [ARM64,X86,EARLY] Control IOVA allocation for PCI devices.
Format: { "0" | "1" } Format: { "0" | "1" }
0 - Try to allocate a 32-bit DMA address first, before 0 - Try to allocate a 32-bit DMA address first, before
falling back to the full range if needed. falling back to the full range if needed.
...@@ -2240,7 +2242,7 @@ ...@@ -2240,7 +2242,7 @@
forcing Dual Address Cycle for PCI cards supporting forcing Dual Address Cycle for PCI cards supporting
greater than 32-bit addressing. greater than 32-bit addressing.
iommu.strict= [ARM64, X86, S390] Configure TLB invalidation behaviour iommu.strict= [ARM64,X86,S390,EARLY] Configure TLB invalidation behaviour
Format: { "0" | "1" } Format: { "0" | "1" }
0 - Lazy mode. 0 - Lazy mode.
Request that DMA unmap operations use deferred Request that DMA unmap operations use deferred
...@@ -2256,7 +2258,7 @@ ...@@ -2256,7 +2258,7 @@
legacy driver-specific options takes precedence. legacy driver-specific options takes precedence.
iommu.passthrough= iommu.passthrough=
[ARM64, X86] Configure DMA to bypass the IOMMU by default. [ARM64,X86,EARLY] Configure DMA to bypass the IOMMU by default.
Format: { "0" | "1" } Format: { "0" | "1" }
0 - Use IOMMU translation for DMA. 0 - Use IOMMU translation for DMA.
1 - Bypass the IOMMU for DMA. 1 - Bypass the IOMMU for DMA.
...@@ -2266,7 +2268,7 @@ ...@@ -2266,7 +2268,7 @@
See comment before marvel_specify_io7 in See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c. arch/alpha/kernel/core_marvel.c.
io_delay= [X86] I/O delay method io_delay= [X86,EARLY] I/O delay method
0x80 0x80
Standard port 0x80 based delay Standard port 0x80 based delay
0xed 0xed
...@@ -2279,28 +2281,28 @@ ...@@ -2279,28 +2281,28 @@
ip= [IP_PNP] ip= [IP_PNP]
See Documentation/admin-guide/nfs/nfsroot.rst. See Documentation/admin-guide/nfs/nfsroot.rst.
ipcmni_extend [KNL] Extend the maximum number of unique System V ipcmni_extend [KNL,EARLY] Extend the maximum number of unique System V
IPC identifiers from 32,768 to 16,777,216. IPC identifiers from 32,768 to 16,777,216.
irqaffinity= [SMP] Set the default irq affinity mask irqaffinity= [SMP] Set the default irq affinity mask
The argument is a cpu list, as described above. The argument is a cpu list, as described above.
irqchip.gicv2_force_probe= irqchip.gicv2_force_probe=
[ARM, ARM64] [ARM,ARM64,EARLY]
Format: <bool> Format: <bool>
Force the kernel to look for the second 4kB page Force the kernel to look for the second 4kB page
of a GICv2 controller even if the memory range of a GICv2 controller even if the memory range
exposed by the device tree is too small. exposed by the device tree is too small.
irqchip.gicv3_nolpi= irqchip.gicv3_nolpi=
[ARM, ARM64] [ARM,ARM64,EARLY]
Force the kernel to ignore the availability of Force the kernel to ignore the availability of
LPIs (and by consequence ITSs). Intended for system LPIs (and by consequence ITSs). Intended for system
that use the kernel as a bootloader, and thus want that use the kernel as a bootloader, and thus want
to let secondary kernels in charge of setting up to let secondary kernels in charge of setting up
LPIs. LPIs.
irqchip.gicv3_pseudo_nmi= [ARM64] irqchip.gicv3_pseudo_nmi= [ARM64,EARLY]
Enables support for pseudo-NMIs in the kernel. This Enables support for pseudo-NMIs in the kernel. This
requires the kernel to be built with requires the kernel to be built with
CONFIG_ARM64_PSEUDO_NMI. CONFIG_ARM64_PSEUDO_NMI.
...@@ -2445,7 +2447,7 @@ ...@@ -2445,7 +2447,7 @@
parameter KASAN will print report only for the first parameter KASAN will print report only for the first
invalid access. invalid access.
keep_bootcon [KNL] keep_bootcon [KNL,EARLY]
Do not unregister boot console at start. This is only Do not unregister boot console at start. This is only
useful for debugging when something happens in the window useful for debugging when something happens in the window
between unregistering the boot console and initializing between unregistering the boot console and initializing
...@@ -2453,7 +2455,7 @@ ...@@ -2453,7 +2455,7 @@
keepinitrd [HW,ARM] See retain_initrd. keepinitrd [HW,ARM] See retain_initrd.
kernelcore= [KNL,X86,IA-64,PPC] kernelcore= [KNL,X86,IA-64,PPC,EARLY]
Format: nn[KMGTPE] | nn% | "mirror" Format: nn[KMGTPE] | nn% | "mirror"
This parameter specifies the amount of memory usable by This parameter specifies the amount of memory usable by
the kernel for non-movable allocations. The requested the kernel for non-movable allocations. The requested
...@@ -2478,7 +2480,7 @@ ...@@ -2478,7 +2480,7 @@
for Movable pages. "nn[KMGTPE]", "nn%", and "mirror" for Movable pages. "nn[KMGTPE]", "nn%", and "mirror"
are exclusive, so you cannot specify multiple forms. are exclusive, so you cannot specify multiple forms.
kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. kgdbdbgp= [KGDB,HW,EARLY] kgdb over EHCI usb debug port.
Format: <Controller#>[,poll interval] Format: <Controller#>[,poll interval]
The controller # is the number of the ehci usb debug The controller # is the number of the ehci usb debug
port as it is probed via PCI. The poll interval is port as it is probed via PCI. The poll interval is
...@@ -2499,7 +2501,7 @@ ...@@ -2499,7 +2501,7 @@
kms, kbd format: kms,kbd kms, kbd format: kms,kbd
kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
kgdboc_earlycon= [KGDB,HW] kgdboc_earlycon= [KGDB,HW,EARLY]
If the boot console provides the ability to read If the boot console provides the ability to read
characters and can work in polling mode, you can use characters and can work in polling mode, you can use
this parameter to tell kgdb to use it as a backend this parameter to tell kgdb to use it as a backend
...@@ -2514,14 +2516,14 @@ ...@@ -2514,14 +2516,14 @@
blank and the first boot console that implements blank and the first boot console that implements
read() will be picked. read() will be picked.
kgdbwait [KGDB] Stop kernel execution and enter the kgdbwait [KGDB,EARLY] Stop kernel execution and enter the
kernel debugger at the earliest opportunity. kernel debugger at the earliest opportunity.
kmac= [MIPS] Korina ethernet MAC address. kmac= [MIPS] Korina ethernet MAC address.
Configure the RouterBoard 532 series on-chip Configure the RouterBoard 532 series on-chip
Ethernet adapter MAC address. Ethernet adapter MAC address.
kmemleak= [KNL] Boot-time kmemleak enable/disable kmemleak= [KNL,EARLY] Boot-time kmemleak enable/disable
Valid arguments: on, off Valid arguments: on, off
Default: on Default: on
Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y,
...@@ -2540,8 +2542,8 @@ ...@@ -2540,8 +2542,8 @@
See also Documentation/trace/kprobetrace.rst "Kernel See also Documentation/trace/kprobetrace.rst "Kernel
Boot Parameter" section. Boot Parameter" section.
kpti= [ARM64] Control page table isolation of user kpti= [ARM64,EARLY] Control page table isolation of
and kernel address spaces. user and kernel address spaces.
Default: enabled on cores which need mitigation. Default: enabled on cores which need mitigation.
0: force disabled 0: force disabled
1: force enabled 1: force enabled
...@@ -2618,7 +2620,8 @@ ...@@ -2618,7 +2620,8 @@
for NPT. for NPT.
kvm-arm.mode= kvm-arm.mode=
[KVM,ARM] Select one of KVM/arm64's modes of operation. [KVM,ARM,EARLY] Select one of KVM/arm64's modes of
operation.
none: Forcefully disable KVM. none: Forcefully disable KVM.
...@@ -2638,22 +2641,22 @@ ...@@ -2638,22 +2641,22 @@
used with extreme caution. used with extreme caution.
kvm-arm.vgic_v3_group0_trap= kvm-arm.vgic_v3_group0_trap=
[KVM,ARM] Trap guest accesses to GICv3 group-0 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-0
system registers system registers
kvm-arm.vgic_v3_group1_trap= kvm-arm.vgic_v3_group1_trap=
[KVM,ARM] Trap guest accesses to GICv3 group-1 [KVM,ARM,EARLY] Trap guest accesses to GICv3 group-1
system registers system registers
kvm-arm.vgic_v3_common_trap= kvm-arm.vgic_v3_common_trap=
[KVM,ARM] Trap guest accesses to GICv3 common [KVM,ARM,EARLY] Trap guest accesses to GICv3 common
system registers system registers
kvm-arm.vgic_v4_enable= kvm-arm.vgic_v4_enable=
[KVM,ARM] Allow use of GICv4 for direct injection of [KVM,ARM,EARLY] Allow use of GICv4 for direct
LPIs. injection of LPIs.
kvm_cma_resv_ratio=n [PPC] kvm_cma_resv_ratio=n [PPC,EARLY]
Reserves given percentage from system memory area for Reserves given percentage from system memory area for
contiguous memory allocation for KVM hash pagetable contiguous memory allocation for KVM hash pagetable
allocation. allocation.
...@@ -2706,7 +2709,7 @@ ...@@ -2706,7 +2709,7 @@
(enabled). Disable by KVM if hardware lacks support (enabled). Disable by KVM if hardware lacks support
for it. for it.
l1d_flush= [X86,INTEL] l1d_flush= [X86,INTEL,EARLY]
Control mitigation for L1D based snooping vulnerability. Control mitigation for L1D based snooping vulnerability.
Certain CPUs are vulnerable to an exploit against CPU Certain CPUs are vulnerable to an exploit against CPU
...@@ -2723,7 +2726,7 @@ ...@@ -2723,7 +2726,7 @@
on - enable the interface for the mitigation on - enable the interface for the mitigation
l1tf= [X86] Control mitigation of the L1TF vulnerability on l1tf= [X86,EARLY] Control mitigation of the L1TF vulnerability on
affected CPUs affected CPUs
The kernel PTE inversion protection is unconditionally The kernel PTE inversion protection is unconditionally
...@@ -2792,7 +2795,7 @@ ...@@ -2792,7 +2795,7 @@
l3cr= [PPC] l3cr= [PPC]
lapic [X86-32,APIC] Enable the local APIC even if BIOS lapic [X86-32,APIC,EARLY] Enable the local APIC even if BIOS
disabled it. disabled it.
lapic= [X86,APIC] Do not use TSC deadline lapic= [X86,APIC] Do not use TSC deadline
...@@ -2800,7 +2803,7 @@ ...@@ -2800,7 +2803,7 @@
back to the programmable timer unit in the LAPIC. back to the programmable timer unit in the LAPIC.
Format: notscdeadline Format: notscdeadline
lapic_timer_c2_ok [X86,APIC] trust the local apic timer lapic_timer_c2_ok [X86,APIC,EARLY] trust the local apic timer
in C2 power state. in C2 power state.
libata.dma= [LIBATA] DMA control libata.dma= [LIBATA] DMA control
...@@ -2924,7 +2927,7 @@ ...@@ -2924,7 +2927,7 @@
lockd.nlm_udpport=M [NFS] Assign UDP port. lockd.nlm_udpport=M [NFS] Assign UDP port.
Format: <integer> Format: <integer>
lockdown= [SECURITY] lockdown= [SECURITY,EARLY]
{ integrity | confidentiality } { integrity | confidentiality }
Enable the kernel lockdown feature. If set to Enable the kernel lockdown feature. If set to
integrity, kernel features that allow userland to integrity, kernel features that allow userland to
...@@ -3031,7 +3034,8 @@ ...@@ -3031,7 +3034,8 @@
logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
Format: <irq> Format: <irq>
loglevel= All Kernel Messages with a loglevel smaller than the loglevel= [KNL,EARLY]
All Kernel Messages with a loglevel smaller than the
console loglevel will be printed to the console. It can console loglevel will be printed to the console. It can
also be changed with klogd or other programs. The also be changed with klogd or other programs. The
loglevels are defined as follows: loglevels are defined as follows:
...@@ -3045,13 +3049,15 @@ ...@@ -3045,13 +3049,15 @@
6 (KERN_INFO) informational 6 (KERN_INFO) informational
7 (KERN_DEBUG) debug-level messages 7 (KERN_DEBUG) debug-level messages
log_buf_len=n[KMG] Sets the size of the printk ring buffer, log_buf_len=n[KMG] [KNL,EARLY]
in bytes. n must be a power of two and greater Sets the size of the printk ring buffer, in bytes.
than the minimal size. The minimal size is defined n must be a power of two and greater than the
by LOG_BUF_SHIFT kernel config parameter. There is minimal size. The minimal size is defined by
also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter LOG_BUF_SHIFT kernel config parameter. There
that allows to increase the default size depending on is also CONFIG_LOG_CPU_MAX_BUF_SHIFT config
the number of CPUs. See init/Kconfig for more details. parameter that allows to increase the default size
depending on the number of CPUs. See init/Kconfig
for more details.
logo.nologo [FB] Disables display of the built-in Linux logo. logo.nologo [FB] Disables display of the built-in Linux logo.
This may be used to provide more screen space for This may be used to provide more screen space for
...@@ -3109,7 +3115,7 @@ ...@@ -3109,7 +3115,7 @@
max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater
than or equal to this physical address is ignored. than or equal to this physical address is ignored.
maxcpus= [SMP] Maximum number of processors that an SMP kernel maxcpus= [SMP,EARLY] Maximum number of processors that an SMP kernel
will bring up during bootup. maxcpus=n : n >= 0 limits will bring up during bootup. maxcpus=n : n >= 0 limits
the kernel to bring up 'n' processors. Surely after the kernel to bring up 'n' processors. Surely after
bootup you can bring up the other plugged cpu by executing bootup you can bring up the other plugged cpu by executing
...@@ -3136,7 +3142,7 @@ ...@@ -3136,7 +3142,7 @@
Format: <first>,<last> Format: <first>,<last>
Specifies range of consoles to be captured by the MDA. Specifies range of consoles to be captured by the MDA.
mds= [X86,INTEL] mds= [X86,INTEL,EARLY]
Control mitigation for the Micro-architectural Data Control mitigation for the Micro-architectural Data
Sampling (MDS) vulnerability. Sampling (MDS) vulnerability.
...@@ -3168,11 +3174,12 @@ ...@@ -3168,11 +3174,12 @@
For details see: Documentation/admin-guide/hw-vuln/mds.rst For details see: Documentation/admin-guide/hw-vuln/mds.rst
mem=nn[KMG] [HEXAGON] Set the memory size. mem=nn[KMG] [HEXAGON,EARLY] Set the memory size.
Must be specified, otherwise memory size will be 0. Must be specified, otherwise memory size will be 0.
mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory mem=nn[KMG] [KNL,BOOT,EARLY] Force usage of a specific amount
Amount of memory to be used in cases as follows: of memory Amount of memory to be used in cases
as follows:
1 for test; 1 for test;
2 when the kernel is not able to see the whole system memory; 2 when the kernel is not able to see the whole system memory;
...@@ -3196,8 +3203,8 @@ ...@@ -3196,8 +3203,8 @@
if system memory of hypervisor is not sufficient. if system memory of hypervisor is not sufficient.
mem=nn[KMG]@ss[KMG] mem=nn[KMG]@ss[KMG]
[ARM,MIPS] - override the memory layout reported by [ARM,MIPS,EARLY] - override the memory layout
firmware. reported by firmware.
Define a memory region of size nn[KMG] starting at Define a memory region of size nn[KMG] starting at
ss[KMG]. ss[KMG].
Multiple different regions can be specified with Multiple different regions can be specified with
...@@ -3206,7 +3213,7 @@ ...@@ -3206,7 +3213,7 @@
mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
memory. memory.
memblock=debug [KNL] Enable memblock debug messages. memblock=debug [KNL,EARLY] Enable memblock debug messages.
memchunk=nn[KMG] memchunk=nn[KMG]
[KNL,SH] Allow user to override the default size for [KNL,SH] Allow user to override the default size for
...@@ -3220,14 +3227,14 @@ ...@@ -3220,14 +3227,14 @@
option. option.
See Documentation/admin-guide/mm/memory-hotplug.rst. See Documentation/admin-guide/mm/memory-hotplug.rst.
memmap=exactmap [KNL,X86] Enable setting of an exact memmap=exactmap [KNL,X86,EARLY] Enable setting of an exact
E820 memory map, as specified by the user. E820 memory map, as specified by the user.
Such memmap=exactmap lines can be constructed based on Such memmap=exactmap lines can be constructed based on
BIOS output or other requirements. See the memmap=nn@ss BIOS output or other requirements. See the memmap=nn@ss
option description. option description.
memmap=nn[KMG]@ss[KMG] memmap=nn[KMG]@ss[KMG]
[KNL, X86, MIPS, XTENSA] Force usage of a specific region of memory. [KNL, X86,MIPS,XTENSA,EARLY] Force usage of a specific region of memory.
Region of memory to be used is from ss to ss+nn. Region of memory to be used is from ss to ss+nn.
If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG], If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG],
which limits max address to nn[KMG]. which limits max address to nn[KMG].
...@@ -3237,11 +3244,11 @@ ...@@ -3237,11 +3244,11 @@
memmap=100M@2G,100M#3G,1G!1024G memmap=100M@2G,100M#3G,1G!1024G
memmap=nn[KMG]#ss[KMG] memmap=nn[KMG]#ss[KMG]
[KNL,ACPI] Mark specific memory as ACPI data. [KNL,ACPI,EARLY] Mark specific memory as ACPI data.
Region of memory to be marked is from ss to ss+nn. Region of memory to be marked is from ss to ss+nn.
memmap=nn[KMG]$ss[KMG] memmap=nn[KMG]$ss[KMG]
[KNL,ACPI] Mark specific memory as reserved. [KNL,ACPI,EARLY] Mark specific memory as reserved.
Region of memory to be reserved is from ss to ss+nn. Region of memory to be reserved is from ss to ss+nn.
Example: Exclude memory from 0x18690000-0x1869ffff Example: Exclude memory from 0x18690000-0x1869ffff
memmap=64K$0x18690000 memmap=64K$0x18690000
...@@ -3251,14 +3258,14 @@ ...@@ -3251,14 +3258,14 @@
like Grub2, otherwise '$' and the following number like Grub2, otherwise '$' and the following number
will be eaten. will be eaten.
memmap=nn[KMG]!ss[KMG] memmap=nn[KMG]!ss[KMG,EARLY]
[KNL,X86] Mark specific memory as protected. [KNL,X86] Mark specific memory as protected.
Region of memory to be used, from ss to ss+nn. Region of memory to be used, from ss to ss+nn.
The memory region may be marked as e820 type 12 (0xc) The memory region may be marked as e820 type 12 (0xc)
and is NVDIMM or ADR memory. and is NVDIMM or ADR memory.
memmap=<size>%<offset>-<oldtype>+<newtype> memmap=<size>%<offset>-<oldtype>+<newtype>
[KNL,ACPI] Convert memory within the specified region [KNL,ACPI,EARLY] Convert memory within the specified region
from <oldtype> to <newtype>. If "-<oldtype>" is left from <oldtype> to <newtype>. If "-<oldtype>" is left
out, the whole region will be marked as <newtype>, out, the whole region will be marked as <newtype>,
even if previously unavailable. If "+<newtype>" is left even if previously unavailable. If "+<newtype>" is left
...@@ -3266,7 +3273,7 @@ ...@@ -3266,7 +3273,7 @@
specified as e820 types, e.g., 1 = RAM, 2 = reserved, specified as e820 types, e.g., 1 = RAM, 2 = reserved,
3 = ACPI, 12 = PRAM. 3 = ACPI, 12 = PRAM.
memory_corruption_check=0/1 [X86] memory_corruption_check=0/1 [X86,EARLY]
Some BIOSes seem to corrupt the first 64k of Some BIOSes seem to corrupt the first 64k of
memory when doing things like suspend/resume. memory when doing things like suspend/resume.
Setting this option will scan the memory Setting this option will scan the memory
...@@ -3278,13 +3285,13 @@ ...@@ -3278,13 +3285,13 @@
affects the same memory, you can use memmap= affects the same memory, you can use memmap=
to prevent the kernel from using that memory. to prevent the kernel from using that memory.
memory_corruption_check_size=size [X86] memory_corruption_check_size=size [X86,EARLY]
By default it checks for corruption in the low By default it checks for corruption in the low
64k, making this memory unavailable for normal 64k, making this memory unavailable for normal
use. Use this parameter to scan for use. Use this parameter to scan for
corruption in more or less memory. corruption in more or less memory.
memory_corruption_check_period=seconds [X86] memory_corruption_check_period=seconds [X86,EARLY]
By default it checks for corruption every 60 By default it checks for corruption every 60
seconds. Use this parameter to check at some seconds. Use this parameter to check at some
other rate. 0 disables periodic checking. other rate. 0 disables periodic checking.
...@@ -3308,7 +3315,7 @@ ...@@ -3308,7 +3315,7 @@
Note that even when enabled, there are a few cases where Note that even when enabled, there are a few cases where
the feature is not effective. the feature is not effective.
memtest= [KNL,X86,ARM,M68K,PPC,RISCV] Enable memtest memtest= [KNL,X86,ARM,M68K,PPC,RISCV,EARLY] Enable memtest
Format: <integer> Format: <integer>
default : 0 <disable> default : 0 <disable>
Specifies the number of memtest passes to be Specifies the number of memtest passes to be
...@@ -3376,7 +3383,7 @@ ...@@ -3376,7 +3383,7 @@
https://repo.or.cz/w/linux-2.6/mini2440.git https://repo.or.cz/w/linux-2.6/mini2440.git
mitigations= mitigations=
[X86,PPC,S390,ARM64] Control optional mitigations for [X86,PPC,S390,ARM64,EARLY] Control optional mitigations for
CPU vulnerabilities. This is a set of curated, CPU vulnerabilities. This is a set of curated,
arch-independent options, each of which is an arch-independent options, each of which is an
aggregation of existing arch-specific options. aggregation of existing arch-specific options.
...@@ -3429,7 +3436,7 @@ ...@@ -3429,7 +3436,7 @@
retbleed=auto,nosmt [X86] retbleed=auto,nosmt [X86]
mminit_loglevel= mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this [KNL,EARLY] When CONFIG_DEBUG_MEMORY_INIT is set, this
parameter allows control of the logging verbosity for parameter allows control of the logging verbosity for
the additional memory initialisation checks. A value the additional memory initialisation checks. A value
of 0 disables mminit logging and a level of 4 will of 0 disables mminit logging and a level of 4 will
...@@ -3437,7 +3444,7 @@ ...@@ -3437,7 +3444,7 @@
so loglevel=8 may also need to be specified. so loglevel=8 may also need to be specified.
mmio_stale_data= mmio_stale_data=
[X86,INTEL] Control mitigation for the Processor [X86,INTEL,EARLY] Control mitigation for the Processor
MMIO Stale Data vulnerabilities. MMIO Stale Data vulnerabilities.
Processor MMIO Stale Data is a class of Processor MMIO Stale Data is a class of
...@@ -3512,7 +3519,7 @@ ...@@ -3512,7 +3519,7 @@
mousedev.yres= [MOUSE] Vertical screen resolution, used for devices mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
reporting absolute coordinates, such as tablets reporting absolute coordinates, such as tablets
movablecore= [KNL,X86,IA-64,PPC] movablecore= [KNL,X86,IA-64,PPC,EARLY]
Format: nn[KMGTPE] | nn% Format: nn[KMGTPE] | nn%
This parameter is the complement to kernelcore=, it This parameter is the complement to kernelcore=, it
specifies the amount of memory used for migratable specifies the amount of memory used for migratable
...@@ -3523,7 +3530,7 @@ ...@@ -3523,7 +3530,7 @@
that the amount of memory usable for all allocations that the amount of memory usable for all allocations
is not too small. is not too small.
movable_node [KNL] Boot-time switch to make hotplugable memory movable_node [KNL,EARLY] Boot-time switch to make hotplugable memory
NUMA nodes to be movable. This means that the memory NUMA nodes to be movable. This means that the memory
of such nodes will be usable only for movable of such nodes will be usable only for movable
allocations which rules out almost all kernel allocations which rules out almost all kernel
...@@ -3547,21 +3554,21 @@ ...@@ -3547,21 +3554,21 @@
[HW] Make the MicroTouch USB driver use raw coordinates [HW] Make the MicroTouch USB driver use raw coordinates
('y', default) or cooked coordinates ('n') ('y', default) or cooked coordinates ('n')
mtrr=debug [X86] mtrr=debug [X86,EARLY]
Enable printing debug information related to MTRR Enable printing debug information related to MTRR
registers at boot time. registers at boot time.
mtrr_chunk_size=nn[KMG] [X86] mtrr_chunk_size=nn[KMG,X86,EARLY]
used for mtrr cleanup. It is largest continuous chunk used for mtrr cleanup. It is largest continuous chunk
that could hold holes aka. UC entries. that could hold holes aka. UC entries.
mtrr_gran_size=nn[KMG] [X86] mtrr_gran_size=nn[KMG,X86,EARLY]
Used for mtrr cleanup. It is granularity of mtrr block. Used for mtrr cleanup. It is granularity of mtrr block.
Default is 1. Default is 1.
Large value could prevent small alignment from Large value could prevent small alignment from
using up MTRRs. using up MTRRs.
mtrr_spare_reg_nr=n [X86] mtrr_spare_reg_nr=n [X86,EARLY]
Format: <integer> Format: <integer>
Range: 0,7 : spare reg number Range: 0,7 : spare reg number
Default : 1 Default : 1
...@@ -3747,10 +3754,10 @@ ...@@ -3747,10 +3754,10 @@
emulation library even if a 387 maths coprocessor emulation library even if a 387 maths coprocessor
is present. is present.
no4lvl [RISCV] Disable 4-level and 5-level paging modes. Forces no4lvl [RISCV,EARLY] Disable 4-level and 5-level paging modes.
kernel to use 3-level paging instead. Forces kernel to use 3-level paging instead.
no5lvl [X86-64,RISCV] Disable 5-level paging mode. Forces no5lvl [X86-64,RISCV,EARLY] Disable 5-level paging mode. Forces
kernel to use 4-level paging instead. kernel to use 4-level paging instead.
noaliencache [MM, NUMA, SLAB] Disables the allocation of alien noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
...@@ -3759,15 +3766,15 @@ ...@@ -3759,15 +3766,15 @@
noalign [KNL,ARM] noalign [KNL,ARM]
noaltinstr [S390] Disables alternative instructions patching noaltinstr [S390,EARLY] Disables alternative instructions
(CPU alternatives feature). patching (CPU alternatives feature).
noapic [SMP,APIC] Tells the kernel to not make use of any noapic [SMP,APIC,EARLY] Tells the kernel to not make use of any
IOAPICs that may be present in the system. IOAPICs that may be present in the system.
noautogroup Disable scheduler automatic task group creation. noautogroup Disable scheduler automatic task group creation.
nocache [ARM] nocache [ARM,EARLY]
no_console_suspend no_console_suspend
[HW] Never suspend the console [HW] Never suspend the console
...@@ -3785,13 +3792,13 @@ ...@@ -3785,13 +3792,13 @@
turn on/off it dynamically. turn on/off it dynamically.
no_debug_objects no_debug_objects
[KNL] Disable object debugging [KNL,EARLY] Disable object debugging
nodsp [SH] Disable hardware DSP at boot time. nodsp [SH] Disable hardware DSP at boot time.
noefi Disable EFI runtime services support. noefi [EFI,EARLY] Disable EFI runtime services support.
no_entry_flush [PPC] Don't flush the L1-D cache when entering the kernel. no_entry_flush [PPC,EARLY] Don't flush the L1-D cache when entering the kernel.
noexec [IA-64] noexec [IA-64]
...@@ -3822,6 +3829,7 @@ ...@@ -3822,6 +3829,7 @@
real-time systems. real-time systems.
no_hash_pointers no_hash_pointers
[KNL,EARLY]
Force pointers printed to the console or buffers to be Force pointers printed to the console or buffers to be
unhashed. By default, when a pointer is printed via %p unhashed. By default, when a pointer is printed via %p
format string, that pointer is "hashed", i.e. obscured format string, that pointer is "hashed", i.e. obscured
...@@ -3846,9 +3854,9 @@ ...@@ -3846,9 +3854,9 @@
the impact of the sleep instructions. This is also the impact of the sleep instructions. This is also
useful when using JTAG debugger. useful when using JTAG debugger.
nohugeiomap [KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings. nohugeiomap [KNL,X86,PPC,ARM64,EARLY] Disable kernel huge I/O mappings.
nohugevmalloc [KNL,X86,PPC,ARM64] Disable kernel huge vmalloc mappings. nohugevmalloc [KNL,X86,PPC,ARM64,EARLY] Disable kernel huge vmalloc mappings.
nohz= [KNL] Boottime enable/disable dynamic ticks nohz= [KNL] Boottime enable/disable dynamic ticks
Valid arguments: on, off Valid arguments: on, off
...@@ -3870,13 +3878,13 @@ ...@@ -3870,13 +3878,13 @@
noinitrd [RAM] Tells the kernel not to load any configured noinitrd [RAM] Tells the kernel not to load any configured
initial RAM disk. initial RAM disk.
nointremap [X86-64, Intel-IOMMU] Do not enable interrupt nointremap [X86-64,Intel-IOMMU,EARLY] Do not enable interrupt
remapping. remapping.
[Deprecated - use intremap=off] [Deprecated - use intremap=off]
nointroute [IA-64] nointroute [IA-64]
noinvpcid [X86] Disable the INVPCID cpu feature. noinvpcid [X86,EARLY] Disable the INVPCID cpu feature.
noiotrap [SH] Disables trapped I/O port accesses. noiotrap [SH] Disables trapped I/O port accesses.
...@@ -3887,19 +3895,19 @@ ...@@ -3887,19 +3895,19 @@
nojitter [IA-64] Disables jitter checking for ITC timers. nojitter [IA-64] Disables jitter checking for ITC timers.
nokaslr [KNL] nokaslr [KNL,EARLY]
When CONFIG_RANDOMIZE_BASE is set, this disables When CONFIG_RANDOMIZE_BASE is set, this disables
kernel and module base offset ASLR (Address Space kernel and module base offset ASLR (Address Space
Layout Randomization). Layout Randomization).
no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page no-kvmapf [X86,KVM,EARLY] Disable paravirtualized asynchronous page
fault handling. fault handling.
no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver no-kvmclock [X86,KVM,EARLY] Disable paravirtualized KVM clock driver
nolapic [X86-32,APIC] Do not enable or use the local APIC. nolapic [X86-32,APIC,EARLY] Do not enable or use the local APIC.
nolapic_timer [X86-32,APIC] Do not use the local APIC timer. nolapic_timer [X86-32,APIC,EARLY] Do not use the local APIC timer.
nomca [IA-64] Disable machine check abort handling nomca [IA-64] Disable machine check abort handling
...@@ -3924,23 +3932,23 @@ ...@@ -3924,23 +3932,23 @@
shutdown the other cpus. Instead use the REBOOT_VECTOR shutdown the other cpus. Instead use the REBOOT_VECTOR
irq. irq.
nopat [X86] Disable PAT (page attribute table extension of nopat [X86,EARLY] Disable PAT (page attribute table extension of
pagetables) support. pagetables) support.
nopcid [X86-64] Disable the PCID cpu feature. nopcid [X86-64,EARLY] Disable the PCID cpu feature.
nopku [X86] Disable Memory Protection Keys CPU feature found nopku [X86] Disable Memory Protection Keys CPU feature found
in some Intel CPUs. in some Intel CPUs.
nopti [X86-64] nopti [X86-64,EARLY]
Equivalent to pti=off Equivalent to pti=off
nopv= [X86,XEN,KVM,HYPER_V,VMWARE] nopv= [X86,XEN,KVM,HYPER_V,VMWARE,EARLY]
Disables the PV optimizations forcing the guest to run Disables the PV optimizations forcing the guest to run
as generic guest with no PV drivers. Currently support as generic guest with no PV drivers. Currently support
XEN HVM, KVM, HYPER_V and VMWARE guest. XEN HVM, KVM, HYPER_V and VMWARE guest.
nopvspin [X86,XEN,KVM] nopvspin [X86,XEN,KVM,EARLY]
Disables the qspinlock slow path using PV optimizations Disables the qspinlock slow path using PV optimizations
which allow the hypervisor to 'idle' the guest on lock which allow the hypervisor to 'idle' the guest on lock
contention. contention.
...@@ -3960,20 +3968,20 @@ ...@@ -3960,20 +3968,20 @@
This is required for the Braillex ib80-piezo Braille This is required for the Braillex ib80-piezo Braille
reader made by F.H. Papenmeier (Germany). reader made by F.H. Papenmeier (Germany).
nosgx [X86-64,SGX] Disables Intel SGX kernel support. nosgx [X86-64,SGX,EARLY] Disables Intel SGX kernel support.
nosmap [PPC] nosmap [PPC,EARLY]
Disable SMAP (Supervisor Mode Access Prevention) Disable SMAP (Supervisor Mode Access Prevention)
even if it is supported by processor. even if it is supported by processor.
nosmep [PPC64s] nosmep [PPC64s,EARLY]
Disable SMEP (Supervisor Mode Execution Prevention) Disable SMEP (Supervisor Mode Execution Prevention)
even if it is supported by processor. even if it is supported by processor.
nosmp [SMP] Tells an SMP kernel to act as a UP kernel, nosmp [SMP,EARLY] Tells an SMP kernel to act as a UP kernel,
and disable the IO APIC. legacy for "maxcpus=0". and disable the IO APIC. legacy for "maxcpus=0".
nosmt [KNL,MIPS,PPC,S390] Disable symmetric multithreading (SMT). nosmt [KNL,MIPS,PPC,S390,EARLY] Disable symmetric multithreading (SMT).
Equivalent to smt=1. Equivalent to smt=1.
[KNL,X86,PPC] Disable symmetric multithreading (SMT). [KNL,X86,PPC] Disable symmetric multithreading (SMT).
...@@ -3983,22 +3991,23 @@ ...@@ -3983,22 +3991,23 @@
nosoftlockup [KNL] Disable the soft-lockup detector. nosoftlockup [KNL] Disable the soft-lockup detector.
nospec_store_bypass_disable nospec_store_bypass_disable
[HW] Disable all mitigations for the Speculative Store Bypass vulnerability [HW,EARLY] Disable all mitigations for the Speculative
Store Bypass vulnerability
nospectre_bhb [ARM64] Disable all mitigations for Spectre-BHB (branch nospectre_bhb [ARM64,EARLY] Disable all mitigations for Spectre-BHB (branch
history injection) vulnerability. System may allow data leaks history injection) vulnerability. System may allow data leaks
with this option. with this option.
nospectre_v1 [X86,PPC] Disable mitigations for Spectre Variant 1 nospectre_v1 [X86,PPC,EARLY] Disable mitigations for Spectre Variant 1
(bounds check bypass). With this option data leaks are (bounds check bypass). With this option data leaks are
possible in the system. possible in the system.
nospectre_v2 [X86,PPC_E500,ARM64] Disable all mitigations for nospectre_v2 [X86,PPC_E500,ARM64,EARLY] Disable all mitigations
the Spectre variant 2 (indirect branch prediction) for the Spectre variant 2 (indirect branch
vulnerability. System may allow data leaks with this prediction) vulnerability. System may allow data
option. leaks with this option.
no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV] Disable no-steal-acc [X86,PV_OPS,ARM64,PPC/PSERIES,RISCV,EARLY] Disable
paravirtualized steal time accounting. steal time is paravirtualized steal time accounting. steal time is
computed, but won't influence scheduler behaviour computed, but won't influence scheduler behaviour
...@@ -4008,7 +4017,7 @@ ...@@ -4008,7 +4017,7 @@
broken timer IRQ sources. broken timer IRQ sources.
no_uaccess_flush no_uaccess_flush
[PPC] Don't flush the L1-D cache after accessing user data. [PPC,EARLY] Don't flush the L1-D cache after accessing user data.
novmcoredd [KNL,KDUMP] novmcoredd [KNL,KDUMP]
Disable device dump. Device dump allows drivers to Disable device dump. Device dump allows drivers to
...@@ -4022,15 +4031,15 @@ ...@@ -4022,15 +4031,15 @@
is set. is set.
no-vmw-sched-clock no-vmw-sched-clock
[X86,PV_OPS] Disable paravirtualized VMware scheduler [X86,PV_OPS,EARLY] Disable paravirtualized VMware
clock and use the default one. scheduler clock and use the default one.
nowatchdog [KNL] Disable both lockup detectors, i.e. nowatchdog [KNL] Disable both lockup detectors, i.e.
soft-lockup and NMI watchdog (hard-lockup). soft-lockup and NMI watchdog (hard-lockup).
nowb [ARM] nowb [ARM,EARLY]
nox2apic [X86-64,APIC] Do not enable x2APIC mode. nox2apic [X86-64,APIC,EARLY] Do not enable x2APIC mode.
NOTE: this parameter will be ignored on systems with the NOTE: this parameter will be ignored on systems with the
LEGACY_XAPIC_DISABLED bit set in the LEGACY_XAPIC_DISABLED bit set in the
...@@ -4068,7 +4077,7 @@ ...@@ -4068,7 +4077,7 @@
purges which is reported from either PAL_VM_SUMMARY or purges which is reported from either PAL_VM_SUMMARY or
SAL PALO. SAL PALO.
nr_cpus= [SMP] Maximum number of processors that an SMP kernel nr_cpus= [SMP,EARLY] Maximum number of processors that an SMP kernel
could support. nr_cpus=n : n >= 1 limits the kernel to could support. nr_cpus=n : n >= 1 limits the kernel to
support 'n' processors. It could be larger than the support 'n' processors. It could be larger than the
number of already plugged CPU during bootup, later in number of already plugged CPU during bootup, later in
...@@ -4079,8 +4088,9 @@ ...@@ -4079,8 +4088,9 @@
nr_uarts= [SERIAL] maximum number of UARTs to be registered. nr_uarts= [SERIAL] maximum number of UARTs to be registered.
numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86] Disable NUMA, Only numa=off [KNL, ARM64, PPC, RISCV, SPARC, X86, EARLY]
set up a single NUMA node spanning all memory. Disable NUMA, Only set up a single NUMA node
spanning all memory.
numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic numa_balancing= [KNL,ARM64,PPC,RISCV,S390,X86] Enable or disable automatic
NUMA balancing. NUMA balancing.
...@@ -4091,7 +4101,7 @@ ...@@ -4091,7 +4101,7 @@
This can be set from sysctl after boot. This can be set from sysctl after boot.
See Documentation/admin-guide/sysctl/vm.rst for details. See Documentation/admin-guide/sysctl/vm.rst for details.
ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. ohci1394_dma=early [HW,EARLY] enable debugging via the ohci1394 driver.
See Documentation/core-api/debugging-via-ohci1394.rst for more See Documentation/core-api/debugging-via-ohci1394.rst for more
info. info.
...@@ -4117,7 +4127,8 @@ ...@@ -4117,7 +4127,8 @@
Once locked, the boundary cannot be changed. Once locked, the boundary cannot be changed.
1 indicates lock status, 0 indicates unlock status. 1 indicates lock status, 0 indicates unlock status.
oops=panic Always panic on oopses. Default is to just kill the oops=panic [KNL,EARLY]
Always panic on oopses. Default is to just kill the
process, but there is a small probability of process, but there is a small probability of
deadlocking the machine. deadlocking the machine.
This will also cause panics on machine check exceptions. This will also cause panics on machine check exceptions.
...@@ -4133,13 +4144,13 @@ ...@@ -4133,13 +4144,13 @@
can be read from sysfs at: can be read from sysfs at:
/sys/module/page_alloc/parameters/shuffle. /sys/module/page_alloc/parameters/shuffle.
page_owner= [KNL] Boot-time page_owner enabling option. page_owner= [KNL,EARLY] Boot-time page_owner enabling option.
Storage of the information about who allocated Storage of the information about who allocated
each page is disabled in default. With this switch, each page is disabled in default. With this switch,
we can turn it on. we can turn it on.
on: enable the feature on: enable the feature
page_poison= [KNL] Boot-time parameter changing the state of page_poison= [KNL,EARLY] Boot-time parameter changing the state of
poisoning on the buddy allocator, available with poisoning on the buddy allocator, available with
CONFIG_PAGE_POISONING=y. CONFIG_PAGE_POISONING=y.
off: turn off poisoning (default) off: turn off poisoning (default)
...@@ -4157,7 +4168,8 @@ ...@@ -4157,7 +4168,8 @@
timeout < 0: reboot immediately timeout < 0: reboot immediately
Format: <timeout> Format: <timeout>
panic_on_taint= Bitmask for conditionally calling panic() in add_taint() panic_on_taint= [KNL,EARLY]
Bitmask for conditionally calling panic() in add_taint()
Format: <hex>[,nousertaint] Format: <hex>[,nousertaint]
Hexadecimal bitmask representing the set of TAINT flags Hexadecimal bitmask representing the set of TAINT flags
that will cause the kernel to panic when add_taint() is that will cause the kernel to panic when add_taint() is
...@@ -4313,7 +4325,7 @@ ...@@ -4313,7 +4325,7 @@
pcbit= [HW,ISDN] pcbit= [HW,ISDN]
pci=option[,option...] [PCI] various PCI subsystem options. pci=option[,option...] [PCI,EARLY] various PCI subsystem options.
Some options herein operate on a specific device Some options herein operate on a specific device
or a set of devices (<pci_dev>). These are or a set of devices (<pci_dev>). These are
...@@ -4582,7 +4594,8 @@ ...@@ -4582,7 +4594,8 @@
Format: { 0 | 1 } Format: { 0 | 1 }
See arch/parisc/kernel/pdc_chassis.c See arch/parisc/kernel/pdc_chassis.c
percpu_alloc= Select which percpu first chunk allocator to use. percpu_alloc= [MM,EARLY]
Select which percpu first chunk allocator to use.
Currently supported values are "embed" and "page". Currently supported values are "embed" and "page".
Archs may support subset or none of the selections. Archs may support subset or none of the selections.
See comments in mm/percpu.c for details on each See comments in mm/percpu.c for details on each
...@@ -4651,12 +4664,12 @@ ...@@ -4651,12 +4664,12 @@
execution priority. execution priority.
ppc_strict_facility_enable ppc_strict_facility_enable
[PPC] This option catches any kernel floating point, [PPC,ENABLE] This option catches any kernel floating point,
Altivec, VSX and SPE outside of regions specifically Altivec, VSX and SPE outside of regions specifically
allowed (eg kernel_enable_fpu()/kernel_disable_fpu()). allowed (eg kernel_enable_fpu()/kernel_disable_fpu()).
There is some performance impact when enabling this. There is some performance impact when enabling this.
ppc_tm= [PPC] ppc_tm= [PPC,EARLY]
Format: {"off"} Format: {"off"}
Disable Hardware Transactional Memory Disable Hardware Transactional Memory
...@@ -4766,7 +4779,7 @@ ...@@ -4766,7 +4779,7 @@
[KNL] Number of legacy pty's. Overwrites compiled-in [KNL] Number of legacy pty's. Overwrites compiled-in
default number. default number.
quiet [KNL] Disable most log messages quiet [KNL,EARLY] Disable most log messages
r128= [HW,DRM] r128= [HW,DRM]
...@@ -4783,17 +4796,17 @@ ...@@ -4783,17 +4796,17 @@
ramdisk_start= [RAM] RAM disk image start address ramdisk_start= [RAM] RAM disk image start address
random.trust_cpu=off random.trust_cpu=off
[KNL] Disable trusting the use of the CPU's [KNL,EARLY] Disable trusting the use of the CPU's
random number generator (if available) to random number generator (if available) to
initialize the kernel's RNG. initialize the kernel's RNG.
random.trust_bootloader=off random.trust_bootloader=off
[KNL] Disable trusting the use of the a seed [KNL,EARLY] Disable trusting the use of the a seed
passed by the bootloader (if available) to passed by the bootloader (if available) to
initialize the kernel's RNG. initialize the kernel's RNG.
randomize_kstack_offset= randomize_kstack_offset=
[KNL] Enable or disable kernel stack offset [KNL,EARLY] Enable or disable kernel stack offset
randomization, which provides roughly 5 bits of randomization, which provides roughly 5 bits of
entropy, frustrating memory corruption attacks entropy, frustrating memory corruption attacks
that depend on stack address determinism or that depend on stack address determinism or
...@@ -5484,7 +5497,7 @@ ...@@ -5484,7 +5497,7 @@
Run specified binary instead of /init from the ramdisk, Run specified binary instead of /init from the ramdisk,
used for early userspace startup. See initrd. used for early userspace startup. See initrd.
rdrand= [X86] rdrand= [X86,EARLY]
force - Override the decision by the kernel to hide the force - Override the decision by the kernel to hide the
advertisement of RDRAND support (this affects advertisement of RDRAND support (this affects
certain AMD processors because of buggy BIOS certain AMD processors because of buggy BIOS
...@@ -5580,7 +5593,7 @@ ...@@ -5580,7 +5593,7 @@
them. If <base> is less than 0x10000, the region them. If <base> is less than 0x10000, the region
is assumed to be I/O ports; otherwise it is memory. is assumed to be I/O ports; otherwise it is memory.
reservetop= [X86-32] reservetop= [X86-32,EARLY]
Format: nn[KMG] Format: nn[KMG]
Reserves a hole at the top of the kernel virtual Reserves a hole at the top of the kernel virtual
address space. address space.
...@@ -5665,7 +5678,7 @@ ...@@ -5665,7 +5678,7 @@
[KNL] Disable ring 3 MONITOR/MWAIT feature on supported [KNL] Disable ring 3 MONITOR/MWAIT feature on supported
CPUs. CPUs.
riscv_isa_fallback [RISCV] riscv_isa_fallback [RISCV,EARLY]
When CONFIG_RISCV_ISA_FALLBACK is not enabled, permit When CONFIG_RISCV_ISA_FALLBACK is not enabled, permit
falling back to detecting extension support by parsing falling back to detecting extension support by parsing
"riscv,isa" property on devicetree systems when the "riscv,isa" property on devicetree systems when the
...@@ -5674,13 +5687,14 @@ ...@@ -5674,13 +5687,14 @@
ro [KNL] Mount root device read-only on boot ro [KNL] Mount root device read-only on boot
rodata= [KNL] rodata= [KNL,EARLY]
on Mark read-only kernel memory as read-only (default). on Mark read-only kernel memory as read-only (default).
off Leave read-only kernel memory writable for debugging. off Leave read-only kernel memory writable for debugging.
full Mark read-only kernel memory and aliases as read-only full Mark read-only kernel memory and aliases as read-only
[arm64] [arm64]
rockchip.usb_uart rockchip.usb_uart
[EARLY]
Enable the uart passthrough on the designated usb port Enable the uart passthrough on the designated usb port
on Rockchip SoCs. When active, the signals of the on Rockchip SoCs. When active, the signals of the
debug-uart get routed to the D+ and D- pins of the usb debug-uart get routed to the D+ and D- pins of the usb
...@@ -5741,7 +5755,7 @@ ...@@ -5741,7 +5755,7 @@
sa1100ir [NET] sa1100ir [NET]
See drivers/net/irda/sa1100_ir.c. See drivers/net/irda/sa1100_ir.c.
sched_verbose [KNL] Enables verbose scheduler debug messages. sched_verbose [KNL,EARLY] Enables verbose scheduler debug messages.
schedstats= [KNL,X86] Enable or disable scheduled statistics. schedstats= [KNL,X86] Enable or disable scheduled statistics.
Allowed values are enable and disable. This feature Allowed values are enable and disable. This feature
...@@ -5856,7 +5870,7 @@ ...@@ -5856,7 +5870,7 @@
non-zero "wait" parameter. See weight_single non-zero "wait" parameter. See weight_single
and weight_many. and weight_many.
skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate skew_tick= [KNL,EARLY] Offset the periodic timer tick per cpu to mitigate
xtime_lock contention on larger systems, and/or RCU lock xtime_lock contention on larger systems, and/or RCU lock
contention on all systems with CONFIG_MAXSMP set. contention on all systems with CONFIG_MAXSMP set.
Format: { "0" | "1" } Format: { "0" | "1" }
...@@ -5987,10 +6001,10 @@ ...@@ -5987,10 +6001,10 @@
1: Fast pin select (default) 1: Fast pin select (default)
2: ATC IRMode 2: ATC IRMode
smt= [KNL,MIPS,S390] Set the maximum number of threads (logical smt= [KNL,MIPS,S390,EARLY] Set the maximum number of threads
CPUs) to use per physical CPU on systems capable of (logical CPUs) to use per physical CPU on systems
symmetric multithreading (SMT). Will be capped to the capable of symmetric multithreading (SMT). Will
actual hardware limit. be capped to the actual hardware limit.
Format: <integer> Format: <integer>
Default: -1 (no limit) Default: -1 (no limit)
...@@ -6012,7 +6026,7 @@ ...@@ -6012,7 +6026,7 @@
sonypi.*= [HW] Sony Programmable I/O Control Device driver sonypi.*= [HW] Sony Programmable I/O Control Device driver
See Documentation/admin-guide/laptops/sonypi.rst See Documentation/admin-guide/laptops/sonypi.rst
spectre_v2= [X86] Control mitigation of Spectre variant 2 spectre_v2= [X86,EARLY] Control mitigation of Spectre variant 2
(indirect branch speculation) vulnerability. (indirect branch speculation) vulnerability.
The default operation protects the kernel from The default operation protects the kernel from
user space attacks. user space attacks.
...@@ -6092,7 +6106,7 @@ ...@@ -6092,7 +6106,7 @@
spectre_v2_user=auto. spectre_v2_user=auto.
spec_rstack_overflow= spec_rstack_overflow=
[X86] Control RAS overflow mitigation on AMD Zen CPUs [X86,EARLY] Control RAS overflow mitigation on AMD Zen CPUs
off - Disable mitigation off - Disable mitigation
microcode - Enable microcode mitigation only microcode - Enable microcode mitigation only
...@@ -6103,7 +6117,7 @@ ...@@ -6103,7 +6117,7 @@
(cloud-specific mitigation) (cloud-specific mitigation)
spec_store_bypass_disable= spec_store_bypass_disable=
[HW] Control Speculative Store Bypass (SSB) Disable mitigation [HW,EARLY] Control Speculative Store Bypass (SSB) Disable mitigation
(Speculative Store Bypass vulnerability) (Speculative Store Bypass vulnerability)
Certain CPUs are vulnerable to an exploit against a Certain CPUs are vulnerable to an exploit against a
...@@ -6199,7 +6213,7 @@ ...@@ -6199,7 +6213,7 @@
#DB exception for bus lock is triggered only when #DB exception for bus lock is triggered only when
CPL > 0. CPL > 0.
srbds= [X86,INTEL] srbds= [X86,INTEL,EARLY]
Control the Special Register Buffer Data Sampling Control the Special Register Buffer Data Sampling
(SRBDS) mitigation. (SRBDS) mitigation.
...@@ -6286,7 +6300,7 @@ ...@@ -6286,7 +6300,7 @@
srcutree.convert_to_big must have the 0x10 bit srcutree.convert_to_big must have the 0x10 bit
set for contention-based conversions to occur. set for contention-based conversions to occur.
ssbd= [ARM64,HW] ssbd= [ARM64,HW,EARLY]
Speculative Store Bypass Disable control Speculative Store Bypass Disable control
On CPUs that are vulnerable to the Speculative On CPUs that are vulnerable to the Speculative
...@@ -6310,7 +6324,7 @@ ...@@ -6310,7 +6324,7 @@
growing up) the main stack are reserved for no other growing up) the main stack are reserved for no other
mapping. Default value is 256 pages. mapping. Default value is 256 pages.
stack_depot_disable= [KNL] stack_depot_disable= [KNL,EARLY]
Setting this to true through kernel command line will Setting this to true through kernel command line will
disable the stack depot thereby saving the static memory disable the stack depot thereby saving the static memory
consumed by the stack hash table. By default this is set consumed by the stack hash table. By default this is set
...@@ -6349,12 +6363,12 @@ ...@@ -6349,12 +6363,12 @@
be used to filter out binaries which have be used to filter out binaries which have
not yet been made aware of AT_MINSIGSTKSZ. not yet been made aware of AT_MINSIGSTKSZ.
stress_hpt [PPC] stress_hpt [PPC,EARLY]
Limits the number of kernel HPT entries in the hash Limits the number of kernel HPT entries in the hash
page table to increase the rate of hash page table page table to increase the rate of hash page table
faults on kernel addresses. faults on kernel addresses.
stress_slb [PPC] stress_slb [PPC,EARLY]
Limits the number of kernel SLB entries, and flushes Limits the number of kernel SLB entries, and flushes
them frequently to increase the rate of SLB faults them frequently to increase the rate of SLB faults
on kernel addresses. on kernel addresses.
...@@ -6414,7 +6428,7 @@ ...@@ -6414,7 +6428,7 @@
This parameter controls use of the Protected This parameter controls use of the Protected
Execution Facility on pSeries. Execution Facility on pSeries.
swiotlb= [ARM,IA-64,PPC,MIPS,X86] swiotlb= [ARM,IA-64,PPC,MIPS,X86,EARLY]
Format: { <int> [,<int>] | force | noforce } Format: { <int> [,<int>] | force | noforce }
<int> -- Number of I/O TLB slabs <int> -- Number of I/O TLB slabs
<int> -- Second integer after comma. Number of swiotlb <int> -- Second integer after comma. Number of swiotlb
...@@ -6424,7 +6438,7 @@ ...@@ -6424,7 +6438,7 @@
wouldn't be automatically used by the kernel wouldn't be automatically used by the kernel
noforce -- Never use bounce buffers (for debugging) noforce -- Never use bounce buffers (for debugging)
switches= [HW,M68k] switches= [HW,M68k,EARLY]
sysctl.*= [KNL] sysctl.*= [KNL]
Set a sysctl parameter, right before loading the init Set a sysctl parameter, right before loading the init
...@@ -6483,11 +6497,11 @@ ...@@ -6483,11 +6497,11 @@
<deci-seconds>: poll all this frequency <deci-seconds>: poll all this frequency
0: no polling (default) 0: no polling (default)
threadirqs [KNL] threadirqs [KNL,EARLY]
Force threading of all interrupt handlers except those Force threading of all interrupt handlers except those
marked explicitly IRQF_NO_THREAD. marked explicitly IRQF_NO_THREAD.
topology= [S390] topology= [S390,EARLY]
Format: {off | on} Format: {off | on}
Specify if the kernel should make use of the cpu Specify if the kernel should make use of the cpu
topology information if the hardware supports this. topology information if the hardware supports this.
...@@ -6728,7 +6742,7 @@ ...@@ -6728,7 +6742,7 @@
can be overridden by a later tsc=nowatchdog. A console can be overridden by a later tsc=nowatchdog. A console
message will flag any such suppression or overriding. message will flag any such suppression or overriding.
tsc_early_khz= [X86] Skip early TSC calibration and use the given tsc_early_khz= [X86,EARLY] Skip early TSC calibration and use the given
value instead. Useful when the early TSC frequency discovery value instead. Useful when the early TSC frequency discovery
procedure is not reliable, such as on overclocked systems procedure is not reliable, such as on overclocked systems
with CPUID.16h support and partial CPUID.15h support. with CPUID.16h support and partial CPUID.15h support.
...@@ -6763,7 +6777,7 @@ ...@@ -6763,7 +6777,7 @@
See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
for more details. for more details.
tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async tsx_async_abort= [X86,INTEL,EARLY] Control mitigation for the TSX Async
Abort (TAA) vulnerability. Abort (TAA) vulnerability.
Similar to Micro-architectural Data Sampling (MDS) Similar to Micro-architectural Data Sampling (MDS)
...@@ -6829,7 +6843,7 @@ ...@@ -6829,7 +6843,7 @@
unknown_nmi_panic unknown_nmi_panic
[X86] Cause panic on unknown NMI. [X86] Cause panic on unknown NMI.
unwind_debug [X86-64] unwind_debug [X86-64,EARLY]
Enable unwinder debug output. This can be Enable unwinder debug output. This can be
useful for debugging certain unwinder error useful for debugging certain unwinder error
conditions, including corrupt stacks and conditions, including corrupt stacks and
...@@ -7019,7 +7033,7 @@ ...@@ -7019,7 +7033,7 @@
Example: user_debug=31 Example: user_debug=31
userpte= userpte=
[X86] Flags controlling user PTE allocations. [X86,EARLY] Flags controlling user PTE allocations.
nohigh = do not allocate PTE pages in nohigh = do not allocate PTE pages in
HIGHMEM regardless of setting HIGHMEM regardless of setting
...@@ -7048,7 +7062,7 @@ ...@@ -7048,7 +7062,7 @@
vector= [IA-64,SMP] vector= [IA-64,SMP]
vector=percpu: enable percpu vector domain vector=percpu: enable percpu vector domain
video= [FB] Frame buffer configuration video= [FB,EARLY] Frame buffer configuration
See Documentation/fb/modedb.rst. See Documentation/fb/modedb.rst.
video.brightness_switch_enabled= [ACPI] video.brightness_switch_enabled= [ACPI]
...@@ -7096,13 +7110,13 @@ ...@@ -7096,13 +7110,13 @@
P Enable page structure init time poisoning P Enable page structure init time poisoning
- Disable all of the above options - Disable all of the above options
vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact vmalloc=nn[KMG] [KNL,BOOT,EARLY] Forces the vmalloc area to have an
size of <nn>. This can be used to increase the exact size of <nn>. This can be used to increase
minimum size (128MB on x86). It can also be used to the minimum size (128MB on x86). It can also be
decrease the size and leave more room for directly used to decrease the size and leave more room
mapped kernel RAM. for directly mapped kernel RAM.
vmcp_cma=nn[MG] [KNL,S390] vmcp_cma=nn[MG] [KNL,S390,EARLY]
Sets the memory size reserved for contiguous memory Sets the memory size reserved for contiguous memory
allocations for the vmcp device driver. allocations for the vmcp device driver.
...@@ -7115,7 +7129,7 @@ ...@@ -7115,7 +7129,7 @@
vmpoff= [KNL,S390] Perform z/VM CP command after power off. vmpoff= [KNL,S390] Perform z/VM CP command after power off.
Format: <command> Format: <command>
vsyscall= [X86-64] vsyscall= [X86-64,EARLY]
Controls the behavior of vsyscalls (i.e. calls to Controls the behavior of vsyscalls (i.e. calls to
fixed addresses of 0xffffffffff600x00 from legacy fixed addresses of 0xffffffffff600x00 from legacy
code). Most statically-linked binaries and older code). Most statically-linked binaries and older
...@@ -7263,13 +7277,13 @@ ...@@ -7263,13 +7277,13 @@
When enabled, memory and cache locality will be When enabled, memory and cache locality will be
impacted. impacted.
writecombine= [LOONGARCH] Control the MAT (Memory Access Type) of writecombine= [LOONGARCH,EARLY] Control the MAT (Memory Access
ioremap_wc(). Type) of ioremap_wc().
on - Enable writecombine, use WUC for ioremap_wc() on - Enable writecombine, use WUC for ioremap_wc()
off - Disable writecombine, use SUC for ioremap_wc() off - Disable writecombine, use SUC for ioremap_wc()
x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of x2apic_phys [X86-64,APIC,EARLY] Use x2apic physical mode instead of
default x2apic cluster mode on platforms default x2apic cluster mode on platforms
supporting x2apic. supporting x2apic.
...@@ -7280,7 +7294,7 @@ ...@@ -7280,7 +7294,7 @@
save/restore/migration must be enabled to handle larger save/restore/migration must be enabled to handle larger
domains. domains.
xen_emul_unplug= [HW,X86,XEN] xen_emul_unplug= [HW,X86,XEN,EARLY]
Unplug Xen emulated devices Unplug Xen emulated devices
Format: [unplug0,][unplug1] Format: [unplug0,][unplug1]
ide-disks -- unplug primary master IDE devices ide-disks -- unplug primary master IDE devices
...@@ -7292,17 +7306,17 @@ ...@@ -7292,17 +7306,17 @@
the unplug protocol the unplug protocol
never -- do not unplug even if version check succeeds never -- do not unplug even if version check succeeds
xen_legacy_crash [X86,XEN] xen_legacy_crash [X86,XEN,EARLY]
Crash from Xen panic notifier, without executing late Crash from Xen panic notifier, without executing late
panic() code such as dumping handler. panic() code such as dumping handler.
xen_msr_safe= [X86,XEN] xen_msr_safe= [X86,XEN,EARLY]
Format: <bool> Format: <bool>
Select whether to always use non-faulting (safe) MSR Select whether to always use non-faulting (safe) MSR
access functions when running as Xen PV guest. The access functions when running as Xen PV guest. The
default value is controlled by CONFIG_XEN_PV_MSR_SAFE. default value is controlled by CONFIG_XEN_PV_MSR_SAFE.
xen_nopvspin [X86,XEN] xen_nopvspin [X86,XEN,EARLY]
Disables the qspinlock slowpath using Xen PV optimizations. Disables the qspinlock slowpath using Xen PV optimizations.
This parameter is obsoleted by "nopvspin" parameter, which This parameter is obsoleted by "nopvspin" parameter, which
has equivalent effect for XEN platform. has equivalent effect for XEN platform.
...@@ -7314,7 +7328,7 @@ ...@@ -7314,7 +7328,7 @@
has equivalent effect for XEN platform. has equivalent effect for XEN platform.
xen_no_vector_callback xen_no_vector_callback
[KNL,X86,XEN] Disable the vector callback for Xen [KNL,X86,XEN,EARLY] Disable the vector callback for Xen
event channel interrupts. event channel interrupts.
xen_scrub_pages= [XEN] xen_scrub_pages= [XEN]
...@@ -7323,7 +7337,7 @@ ...@@ -7323,7 +7337,7 @@
with /sys/devices/system/xen_memory/xen_memory0/scrub_pages. with /sys/devices/system/xen_memory/xen_memory0/scrub_pages.
Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT. Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.
xen_timer_slop= [X86-64,XEN] xen_timer_slop= [X86-64,XEN,EARLY]
Set the timer slop (in nanoseconds) for the virtual Xen Set the timer slop (in nanoseconds) for the virtual Xen
timers (default is 100000). This adjusts the minimum timers (default is 100000). This adjusts the minimum
delta of virtualized Xen timers, where lower values delta of virtualized Xen timers, where lower values
...@@ -7376,7 +7390,7 @@ ...@@ -7376,7 +7390,7 @@
host controller quirks. Meaning of each bit can be host controller quirks. Meaning of each bit can be
consulted in header drivers/usb/host/xhci.h. consulted in header drivers/usb/host/xhci.h.
xmon [PPC] xmon [PPC,EARLY]
Format: { early | on | rw | ro | off } Format: { early | on | rw | ro | off }
Controls if xmon debugger is enabled. Default is off. Controls if xmon debugger is enabled. Default is off.
Passing only "xmon" is equivalent to "xmon=early". Passing only "xmon" is equivalent to "xmon=early".
......
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