Re: [PATCH v2] x86: remove the BIOS memory corruption check feature

[Thorsten Blum <blum@kernel.org>]

On Mon, Jul 20, 2026 at 04:41:05PM -0400, Luiz Capitulino wrote:
> By default, the BIOS memory corruption check works by reserving the
> first 64 KiB physical area from memblock, zeroing it and then scanning it
> periodically.
> 
> However, this functionality has been broken since v5.13 by two commits:
> 
> - Commit a799c2bd29d1 ("x86/setup: Consolidate early memory reservations").
>   Moved trim_low_memory_range() into early_reserve_memory(), which runs
>   earlier in setup_arch(), causing the first 64 KiB to be reserved (when
>   CONFIG_X86_RESERVE_LOW=64) before setup_bios_corruption_check() runs
> 
> - Commit f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM").
>   Hardcodes the reservation of the first 64 KiB early in
>   early_reserve_memory()
> 
> It might be possible to get this feature to work by allowing
> setup_bios_corruption_check() to run first, but it's just not worth it
> given that the kernel will never access this memory area anyways.
> 
> Signed-off-by: Luiz Capitulino <luizcap@redhat.com>
> ---
> 
> Changelog
> =========
> 
> v2
> - Rebase against latest Linus tree (v7.2-rc4)
> - Improve changelog
> 
>  .../admin-guide/kernel-parameters.txt         |  23 ---
>  arch/x86/Kconfig                              |  30 ---
>  arch/x86/configs/i386_defconfig               |   1 -
>  arch/x86/configs/x86_64_defconfig             |   1 -
>  arch/x86/include/asm/bios_ebda.h              |  17 --
>  arch/x86/include/asm/setup.h                  |   1 -
>  arch/x86/kernel/Makefile                      |   2 -
>  arch/x86/kernel/check.c                       | 187 ------------------
>  arch/x86/kernel/setup.c                       |   4 -
>  9 files changed, 266 deletions(-)
>  delete mode 100644 arch/x86/kernel/check.c

Hi Luiz,

v2 no longer applies to mainline - are you planning to rebase it for v3?

Regarding the changelog: did you consider that the check is only broken
for the default size? Booting with

  memory_corruption_check=1 memory_corruption_check_size=256K

still works and I get:

  check: Scanning 1 areas for low memory corruption
  check: Scanning for low memory corruption every 60 seconds

Thanks,
Thorsten