• Alexey Gladkov's avatar
    moduleparam: Save information about built-in modules in separate file · 898490c0
    Alexey Gladkov authored
    Problem:
    
    When a kernel module is compiled as a separate module, some important
    information about the kernel module is available via .modinfo section of
    the module.  In contrast, when the kernel module is compiled into the
    kernel, that information is not available.
    
    Information about built-in modules is necessary in the following cases:
    
    1. When it is necessary to find out what additional parameters can be
    passed to the kernel at boot time.
    
    2. When you need to know which module names and their aliases are in
    the kernel. This is very useful for creating an initrd image.
    
    Proposal:
    
    The proposed patch does not remove .modinfo section with module
    information from the vmlinux at the build time and saves it into a
    separate file after kernel linking. So, the kernel does not increase in
    size and no additional information remains in it. Information is stored
    in the same format as in the separate modules (null-terminated string
    array). Because the .modinfo section is already exported with a separate
    modules, we are not creating a new API.
    
    It can be easily read in the userspace:
    
    $ tr '\0' '\n' < modules.builtin.modinfo
    ext4.softdep=pre: crc32c
    ext4.license=GPL
    ext4.description=Fourth Extended Filesystem
    ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
    ext4.alias=fs-ext4
    ext4.alias=ext3
    ext4.alias=fs-ext3
    ext4.alias=ext2
    ext4.alias=fs-ext2
    md_mod.alias=block-major-9-*
    md_mod.alias=md
    md_mod.description=MD RAID framework
    md_mod.license=GPL
    md_mod.parmtype=create_on_open:bool
    md_mod.parmtype=start_dirty_degraded:int
    ...
    Co-Developed-by: default avatarGleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
    Signed-off-by: default avatarGleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
    Signed-off-by: default avatarAlexey Gladkov <gladkov.alexey@gmail.com>
    Acked-by: default avatarJessica Yu <jeyu@kernel.org>
    Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
    898490c0
vmlinux.lds.h 27.5 KB