Re: [RFC PATCH 3/3] x86, boot: Change the BIOS corruption checkerto scan 640K

From: H. Peter Anvin
Date: Tue Nov 12 2013 - 02:20:03 EST


On 11/11/2013 08:07 PM, Ingo Molnar wrote:
> I agree with your patches so far, and I'd suggest we go even further: I'd
> say the config option is now a misnomer, it should probably be renamed to
> CONFIG_X86_FORCE_RESERVE_BIOS_LOW_1MB=y or so.

Why is that? It doesn't seem to make much sense to me. I think the
current option names seem to be just fine, but perhaps I'm missing
something.

> Btw., should we also force-reserve the remaining bits over 640K..1MB, if
> they are not marked as reserved in the memory maps, or do we already
> force-reserve them somewhere?

We do, in trim_bios_range(). We treat it as available for I/O
assignments, since that is necessary on some systems.

> The CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK=y option and the
> memory_corruption_check=1 boot option then allow the activation of the low
> memory corrupion checker - which debug facility can be used on systems
> where someone wants to live dangerously and not reserve the low 1MB of RAM
> to the firmware.

That is indeed what this patch does, I think...

-hpa


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