Re: [PATCH] panic.c: export panic_on_oops

Ingo Molnar
2009-10-12T19:18:43Z

* Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net> wrote:

> > I wish it worked on any of the 10+ x86 systems i have. Is there
> > anyone who'd be interested in exploring whether warm BIOS reboots
> > work _anywhere_?
>
> AFAIK memory clearing is default off in coreboot for non-ECC RAM and
> default on for ECC RAM (to avoid parity errors on read, but that can
> probably be worked around). Unless I'm mistaken, the SeaBIOS BIOS
> compatibility layer on top of coreboot doesn't erase RAM at all, so
> contents can survive.
>
> No idea about classic AMI/Award/Phoenix/Insyde/whatever BIOS, though.

I wouldnt mind to support this for coreboot too, but it will only be
practical if there's at least one standard BIOS out of the many i run
that supports warm reboot in practice ...

Can try a test-patch on all of those systems btw. - we do support
warm-reboot on x86 in arch/x86/kernel/reboot.c:

/* Write 0x1234 to absolute memory location 0x472. The BIOS reads
this on booting to tell it to "Bypass memory test (also warm
boot)". This seems like a fairly standard thing that gets set by
REBOOT.COM programs, and the previous reset routine did this
too. */
*((unsigned short *)0x472) = reboot_mode;

But someone would have to come up with a test-patch to prove whether it
works really works.

Ingo