[Crash-utility] Re: crash with Xen dom0 image from kdump

[Dave Anderson]

Horms wrote:

> On Wed, Jun 14, 2006 at 10:46:45AM +0900, Simon Horman [Horms] wrote:
> > On Mon, Jun 12, 2006 at 01:41:07PM +0900, Kazuo Moriwaka wrote:
> > > Hi,
> > >
> > > I'm not clear about shadow mode; are vcpu->arch.shadow_table need for
> > > shadow-mode domains?
> >
> > To be perfectly honest, I'm not clear about it either.
> > The code below probably does not cover shadow mode, but
> > it should be easy enough to fix, probably using vcpu->arch.shadow_table
> > as you suggest. I'll look into it some more.
>
> After talking things over a little with Yamahata-san (who works on
> xen-ia64), it seems that using vcpu->arch.guest_table is correct.
> I guess we shall see.
>
> I added some code to kdump to have it record CR3 for dom0. This is
> done using a second note in the per-cpu notes area, which for now
> just stores a single 4byte entity, the mfn of that CPU in dom0
> if it was present in dom0.
>
> I have made a dump available that includes this. The tarball
> also includes the kernels, xen, symbol files, and patches to xen.
> If you want to find the cr3 saving code its in ./arch/x86/crash.c
>
> I plan to post this update to xen-devel shortly, hopefully tomorrow,
> after upporting to the latest xen tree (I'm still working off about
> 3 weeks ago's tree).
>
> http://packages.vergenet.net/tmp/xen-unstable.hg+kexec-20060616.tar.bz2
>

Thanks -- I'm downloading this, and will try to look at it soon.

I still think, though, that the cr3 value is useless as a starting
point for shadow-pagetable kernels, and we'll end up revisiting
this again later.

Having the "pfn_to_mfn_frame_list_list" mfn value from the shared,
per-domain, "arch_shared_info" structure(s) would cover both
writable and shadow pagetable kernels.

Also, I'm still curious, (I haven't looked at the patcheds in the tar.bz2 file),
does your kexec/kdump kernel get kicked off

(1) when the hypervisor crashes,
(2) when the dom0 kernel crashes, or
(3) both?

Dave




> --
> $B@>Lg(B $BJuRX(B ($B%5%$%b%s!&%[!<%^%s(B) | Simon Horman (Horms)