[Crash-utility] [PATCH 0/2] qemu: Parse necessary sections in crash added in qemu

[Dave Anderson]

----- Original Message -----
> Qemu migration code added new sections to add features
> for live migration of VM. For loading vmcore file captured
> with 'virsh dump' we need to parse these sections in crash.
> 
> This series contains two patches, which parse these sections:
> 
> patch1: parse 'vm_configuration' section
> patch2: parse 'vm_footer' section
> 
>  qemu-load.c |   20 ++++++++++++++++++++
>  qemu-load.h |    4 +++-
>  2 files changed, 23 insertions(+), 1 deletion(-)
> 
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Hi Pankaj,

I suppose I can take the patch.  But, given the advent of "virsh dump --memory-only" 
back in 2012, and more recently, Oleg's added support for QEMU ramdumps by specifying
a memory-backend-file object to the qemu-kvm command:

  commit 89ed9d0a7f7da4578294a492c1ad857244ce7352
  Author: Dave Anderson <anderson at redhat.com>
  Date:   Wed May 4 11:50:19 2016 -0400

    Introduction of support for "live" ramdump files, such as those that
    are specified by the QEMU mem-path argument of a memory-backend-file
    object.  This allows the running of a live crash session against a
    QEMU guest from the host machine.  In this example, the /tmp/MEM file
    on a QEMU host represents the guest's physical memory:
    
      $ qemu-kvm ...other-options... \
      -object memory-backend-file,id=MEM,size=128m,mem-path=/tmp/MEM,share=on \
      -numa node,memdev=MEM -m 128
    
    and a live session run can be run against the guest kernel like so:
    
      $ crash <path-to-guest-vmlinux> live:/tmp/MEM at 0
    
    By prepending the ramdump image name with "live:", the crash session will
    act as if it were running a normal live session.
    (oleg at redhat.com)

And if the guest above crashed, the leftover file can be used as a regular
ramdump dumpfile:

  commit 67a815b8749fbd5c99c29d24b4e699b1d618ddbf
  Author: Dave Anderson <anderson at redhat.com>
  Date:   Wed May 4 14:34:53 2016 -0400

    Added support for x86_64 ramdump files.  Without the patch, the crash
    session fails immediately with the message "ramdump: unsupported
    machine type: X86_64".
    (anderson at redhat.com)


So I don't know why anybody would ever want to use the old "kvmdump" format?
It's for all practical purposes deprecated, not to mention that it's really 
an unsuitable excuse for a crash dumpfile.

Dave