ACPI: delete the "acpi=ht" boot option

acpi=ht was important in 2003 -- before ACPI was
universally deployed and enabled by default in
the major Linux distributions.

At that time, there were a fair number of people who
or chose to, or needed to, run with acpi=off,
yet also wanted access to Hyper-threading.

Today we find that many invocations of "acpi=ht"
are accidental, and thus is it possible that it
is doing more harm than good.

In 2.6.34, we warn on invocation of acpi=ht.
In 2.6.35, we delete the boot option.
Signed-off-by: Len Brown <len.brown@intel.com>

Documentation/kernel-parameters.txt

@@ -143,11 +143,10 @@ and is between 256 and 4096 characters. It is defined in the file
 
 	acpi=		[HW,ACPI,X86]
 			Advanced Configuration and Power Interface
-			Format: { force | off | ht | strict | noirq | rsdt }
+			Format: { force | off | strict | noirq | rsdt }
 			force -- enable ACPI if default was off
 			off -- disable ACPI if default was on
 			noirq -- do not use ACPI for IRQ routing
-			ht -- run only enough ACPI to enable Hyper Threading
 			strict -- Be less tolerant of platforms that are not
 				strictly ACPI specification compliant.
 			rsdt -- prefer RSDT over (default) XSDT

arch/ia64/include/asm/acpi.h

@@ -94,7 +94,6 @@ ia64_acpi_release_global_lock (unsigned int *lock)
 #define acpi_noirq 0	/* ACPI always enabled on IA64 */
 #define acpi_pci_disabled 0 /* ACPI PCI always enabled on IA64 */
 #define acpi_strict 1	/* no ACPI spec workarounds on IA64 */
-#define acpi_ht 0	/* no HT-only mode on IA64 */
 #endif
 #define acpi_processor_cstate_check(x) (x) /* no idle limits on IA64 :) */
 static inline void disable_acpi(void) { }

arch/x86/include/asm/acpi.h

@@ -85,7 +85,6 @@ extern int acpi_ioapic;
 extern int acpi_noirq;
 extern int acpi_strict;
 extern int acpi_disabled;
-extern int acpi_ht;
 extern int acpi_pci_disabled;
 extern int acpi_skip_timer_override;
 extern int acpi_use_timer_override;
@@ -97,7 +96,6 @@ void acpi_pic_sci_set_trigger(unsigned int, u16);
 static inline void disable_acpi(void)
 {
 	acpi_disabled = 1;
-	acpi_ht = 0;
 	acpi_pci_disabled = 1;
 	acpi_noirq = 1;
 }

arch/x86/kernel/acpi/boot.c

@@ -62,7 +62,6 @@ EXPORT_SYMBOL(acpi_disabled);
 int acpi_noirq;				/* skip ACPI IRQ initialization */
 int acpi_pci_disabled;		/* skip ACPI PCI scan and IRQ initialization */
 EXPORT_SYMBOL(acpi_pci_disabled);
-int acpi_ht __initdata = 1;	/* enable HT */
 
 int acpi_lapic;
 int acpi_ioapic;
@@ -1460,9 +1459,8 @@ void __init acpi_boot_table_init(void)
 
 	/*
 	 * If acpi_disabled, bail out
-	 * One exception: acpi=ht continues far enough to enumerate LAPICs
 	 */
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return; 
 
 	/*
@@ -1493,9 +1491,8 @@ int __init early_acpi_boot_init(void)
 {
 	/*
 	 * If acpi_disabled, bail out
-	 * One exception: acpi=ht continues far enough to enumerate LAPICs
 	 */
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return 1;
 
 	/*
@@ -1513,9 +1510,8 @@ int __init acpi_boot_init(void)
 
 	/*
 	 * If acpi_disabled, bail out
-	 * One exception: acpi=ht continues far enough to enumerate LAPICs
 	 */
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return 1;
 
 	acpi_table_parse(ACPI_SIG_BOOT, acpi_parse_sbf);
@@ -1550,21 +1546,12 @@ static int __init parse_acpi(char *arg)
 	/* acpi=force to over-ride black-list */
 	else if (strcmp(arg, "force") == 0) {
 		acpi_force = 1;
-		acpi_ht = 1;
 		acpi_disabled = 0;
 	}
 	/* acpi=strict disables out-of-spec workarounds */
 	else if (strcmp(arg, "strict") == 0) {
 		acpi_strict = 1;
 	}
-	/* Limit ACPI just to boot-time to enable HT */
-	else if (strcmp(arg, "ht") == 0) {
-		if (!acpi_force) {
-			printk(KERN_WARNING "acpi=ht will be removed in Linux-2.6.35\n");
-			disable_acpi();
-		}
-		acpi_ht = 1;
-	}
 	/* acpi=rsdt use RSDT instead of XSDT */
 	else if (strcmp(arg, "rsdt") == 0) {
 		acpi_rsdt_forced = 1;

arch/x86/lguest/boot.c

@@ -1391,7 +1391,6 @@ __init void lguest_init(void)
 #endif
 #ifdef CONFIG_ACPI
 	acpi_disabled = 1;
-	acpi_ht = 0;
 #endif
 
 	/*

drivers/acpi/tables.c

@@ -213,7 +213,7 @@ acpi_table_parse_entries(char *id,
 	unsigned long table_end;
 	acpi_size tbl_size;
 
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return -ENODEV;
 
 	if (!handler)
@@ -280,7 +280,7 @@ int __init acpi_table_parse(char *id, acpi_table_handler handler)
 	struct acpi_table_header *table = NULL;
 	acpi_size tbl_size;
 
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return -ENODEV;
 
 	if (!handler)