Re: [PATCH] kexec: Avoid overwriting the current pgd (x86_64)

["Magnus Damm" <magnus.damm@gmail.com>]

[re-added fastboot list]

On 02 May 2006 08:45:59 +0200, Andi Kleen <ak@suse.de> wrote:
> Magnus Damm <magnus@valinux.co.jp> writes:
>
> > --===============82697867595349228==
> >
> > kexec: Avoid overwriting the current pgd (x86_64)
> >
> > This patch upgrades the x86_64-specific kexec code to avoid overwriting the
> > current pgd. Overwriting the current pgd is bad when CONFIG_CRASH_DUMP is used
> > to start a secondary kernel that dumps the memory of the previous kernel.
>
> Why is it bad?

Because in the kdump case (CONFIG_CRASH_DUMP) we store the memory
contents of the crashed kernel somewhere to later on be able to
analyze it. And it makes sense to avoid overwriting things because we
want to analyze the _original_ state when the kernel crashed, not some
half-overwritten state.

Thanks,

/ magnus
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