* 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 transparently. Basically a bit like kexec, just more convenient and it also goes through the BIOS warm reset, so it might work better than kexec ... Thanks, Ingo
