Re: [PATCH v3] x86/corruption-check: Remove the BIOS memory corruption check feature

[Borislav Petkov]

On Sat, Oct 10, 2026 at 11:36:04AM -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 in its default configuration
> 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 the default case 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 the first 64 KiB area anyway.
> 
> Lastly, note that it's possible to get the corruption check to work with
> a different region by passing memory_corruption_check_size=. However,
> the main goal of the feature was to check the first 64 KiB. Besides,
> the region picked will be almost random as setup_bios_corruption_check()
> will pick a region by size.

And?

Do I want this or should it be fixed or the first 64K are not worth it to
check or...?

That whole "rationale" is not really clear to me. Yes, it is broken,
apparently. So let's remove it but we might get it work still... So which is
it and why?

-- 
Regards/Gruss,
    Boris.

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