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

[Kazuo Moriwaka]

Hi, 

From: Kazuo Moriwaka <moriwaka at valinux.co.jp>
Subject: Re: crash with Xen dom0 image from kdump
Date: Fri, 02 Jun 2006 11:51:40 +0900 (JST)

> Hello Dave,
> # I append crash-utility list to Cc
> 
> From: Dave Anderson <anderson at redhat.com>
> Subject: Re: crash with Xen dom0 image from kdump
> Date: Thu, 01 Jun 2006 08:39:01 -0400
> 
> > Kazuo Moriwaka wrote:
> > 
> > > Hello,
> > >
> > > From: Dave Anderson <anderson at redhat.com>
> > > Subject: Re: crash with Xen dom0 image from kdump
> > > Date: Wed, 31 May 2006 16:20:15 -0400
> > >
> > > >
> > > > Hey guys,
> > > >
> > > > I've got the vmcore file from which Kazuo generated the
> > > > "simulated" xendump dumpfile.  I have a question regarding
> > > > the makeup of the the vmcore file -- are the physical addresses
> > > > referred to by each PT_LOAD segment based upon:
> > > >
> > > > 1. machine addresses, or
> > > > 2. pseudo-physical addresses as perceived by the dom0 vmlinux kernel?
> > > >
> > > > Dave
> > >
> > > It's 1.
> > > vmcore is made by kexec-ed linux kernel (not on xen, but on machine) kdump.
> > > The kernel doesn't know about xen or domains except register info.
> > > Register info is for dom0.
> > >
> > 
> > Ok, good...
> > 
> > Next question -- how did you find dom0's phys_to_machine_mapping[]
> > array from the vmcore in order to create the xendump?

# I forget to write first process.. 

I find idle domain's (similar to idle thread) page table.  
It's machine address is xen symbol 'idle_pg_table' - PAGE_OFFSET(in
x86_32, it's 0xff000000).

In xen virtual address, I find 'dom0'.

> I use xen executable binary with symbols to find 'dom0' global symbol
> in xen.
> In x86_32 arch, dom0->vcpu[0].arch->guest_table has pagetable address
> for domain0 guest kernel.  
> After it, I found 'phys_to_machine_mapping'.  
> For other domains, 'domain_list' is point list of struct domain.
> 
> I'll attach my latest dom0cut script.  'dom0cut_x86_32.py' contains
> names of symbols and structs to get dom0 image.
> 
> > > p.s.
> > > Do you have any plan to support xen hypervisor itself with crash?
> > > If there's, I want to help it.
> > >
> > 
> > I don't -- at least at this time.  (My next primary task is to get crash
> > working with x86 PAE kernels.)
> > 
> > But it would be an interesting project
> > to undertake.  I'm not sure whether or how it would cleanly fit into
> > the crash source code, or whether it should be an executable of
> > its own.  But by all means, if you want to undertake the task, be
> > my guest!
> 
> I'm also not sure about them, yet.  In anyway, at first, I'll help you to
> support xen's vmcore format.  
> It is also a part of a way to support xen hypervisor.
> 
> regards,
> -- 
> Kazuo Moriwaka <moriwaka at valinux.co.jp>
-- 
Kazuo Moriwaka <moriwaka at valinux.co.jp>