[PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic
mingo at elte.hu
Wed Jan 26 09:00:30 EST 2011
* Ahmed S. Darwish <darwish.07 at gmail.com> wrote:
> > Also, have you tried BIOS warm reset vector, which is supposed to reboot without
> > clearing RAM contents - how well does it work in practice on typical laptops? If
> > on crash we could reboot without memory getting cleared that would open up a
> > vast area of space to store the kernel log into (RAM).
> AFAIK, the lmode->rmode transition is more forward-compatible.
> It seems the only place warm boot was documented is in the Intel MP spec, a
> 12-years old document long obsoleted by ACPI. Meanwhile, the real-mode transition
> is rigorously documented in the current Intel and AMD manuals, albeit in kind of a
> holier-than-thou approach.
I mean, use the warm reset vector to truly reset the box.
Then, once a stable known-good kernel boots, *that* kernel can then recover all the
log data which is sitting in a well-known place in RAM, automatically and
Basically a bit like kexec, just more convenient and it also goes through the BIOS
warm reset, so it might work better than kexec ...
More information about the kexec