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

[Dave Anderson]

BTW, this footerSecId variable should be declared as ATTRIBUTE_UNUSED:

$ make warn
... [ cut ] ...
cc -c -g -DX86_64 -DLZO -DSNAPPY -DGDB_7_6  qemu-load.c -Wall -O2 -Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security 
qemu-load.c: In function 'qemu_load':
qemu-load.c:976:13: warning: unused variable 'footerSecId' [-Wunused-variable]
    uint32_t footerSecId = get_be32 (fp);
...   

Dave


----- Original Message -----
> 
> 
> ----- 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(-)
> > 
> > --
> > Crash-utility mailing list
> > Crash-utility at redhat.com
> > https://www.redhat.com/mailman/listinfo/crash-utility
> > 
> 
> 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
> 
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