Re: [PATCH RFC] x86: check for and defend against BIOS memory corruption

From: RafaÅ MiÅecki
Date: Fri Aug 29 2008 - 02:26:23 EST


2008/8/28 Jeremy Fitzhardinge <jeremy@xxxxxxxx>:
> Some BIOSes have been observed to corrupt memory in the low 64k. This
> patch does two things:
> - Reserves all memory which does not have to be in that area, to
> prevent it from being used as general memory by the kernel. Things
> like the SMP trampoline are still in the memory, however.
> - Clears the reserved memory so we can observe changes to it.
> - Adds a function check_for_bios_corruption() which checks and reports on
> memory becoming unexpectedly non-zero. Currently it's called in the
> x86 fault handler, and the powermanagement debug output.
>
> RFC: What other places should we check for corruption in?
>
> [ Alan, RafaÅ: could you check you see:
> 1: corruption messages
> 2: no crashes
> Thanks -J
> ]

I was trying my best to crash system with this patch applied and failed :)

Works great.

Just wonder if I should expect any printk from
check_for_bios_corruption? I do not see any:

zajec@sony:~> dmesg | grep -i corr
scanning 2 areas for BIOS corruption

--
RafaÅ MiÅecki
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