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

[Horms]

On Fri, Jun 02, 2006 at 09:28:07AM -0400, Dave Anderson wrote:
> Kazuo Moriwaka wrote:
> 
> With a xendump, the phys_to_machine_mapping array can be
> found by following the page tables from any of the cr3 values
> found in the dump header.
> 
> It would seem simple enough to have the xen/kdump code store
> a legitimate dom0 cr3 value somewhere in the ELF header.  Would
> that be possible to explore?  Note that I'm not really interested
> in the other guest domains, at least at this point, but I could see
> it potentially helpful to recreate the crash environment for the
> guest domains as well, so perhap an array of per-domain cr3
> values in an ELF header note section would be possible?

I haven't looked into this, but yes I think that should be quite
possible as I believe that dom0's cr3 is stored in the hypervisor
somewhere. The main problem (for me) is where to put the extra crash
note and how to add it without having to modify the user-space kexec
tool - currently that code does not need to be modified in order to work
with xen. Would it be enough to have it stored in a symbol in the
hypervisor (to be honest I don't really understand why crash notes are
needed at all given that there is a symbol table)? Or alternatively,
could you give me suggestions on the crash-note front? I'll chase up
where dom0's cr3 is currently saved.

-- 
Horms                                           http://www.vergenet.net/~horms/