[Crash-utility] How to open 32 bit dom0 kdump....

[Dave Anderson]

----- "Feng LI" <funglee at gmail.com> wrote:

> Thanks Dave,
> 
> I had tried another combination: 32 bit Xen kernel with 32 bit Dom0
> kernel, but I have the similar issue. The vmcore file is still in 64
> bit format. (Our system has a large memory configuration 8GB-192GB),
> Is there any way I can generate elf32 vmcore file ?
> 

OK, now I'm thinking mabye we've got a regression of some sort.  The
bare-metal kdump procedure is designed to use the 64-bit vmcore format
all of the time because physical memory beyond the 4GB limit cannot
be referenced using the fields in a 32-bit vmcore header.

However, you can configure 32-bit by modifying /etc/sysconfig/kdump here:

  # Example:
  #   KEXEC_ARGS="--elf32-core-headers"
  KEXEC_ARGS=" --args-linux"

by making KEXEC_ARGS=" --args-linux --elf32-core-headers"

But before doing that, can you try applying the attached patch to
the crash utility?

Thanks,
  Dave


> Thanks.
> 
> 
> On Fri, Sep 10, 2010 at 5:03 PM, Dave Anderson < anderson at redhat.com >
> wrote:
> 
> 
> 
> 
> ----- "Feng LI" < funglee at gmail.com > wrote:
> 
> 
> > Thanks Dave.
> >
> > I attached the output of elfread -a with this email...
> 
> Hmmm -- now that I think about it, it's seems that the crash
> utility has never supported dom0 vmcores generated from this
> type of Xen hypervisor/dom0 combination.
> 
> Red Hat kernel versions come with the xen.gz and vmlinuz files
> packaged together, i.e., both 64-bit or both 32-bit:
> 
> # rpm -qpl kernel-xen-2.6.18-219.el5.x86_64.rpm
> /boot/.vmlinuz-2.6.18-219.el5xen.hmac
> /boot/System.map-2.6.18-219.el5xen
> /boot/config-2.6.18-219.el5xen
> /boot/symvers-2.6.18-219.el5xen.gz
> /boot/vmlinuz-2.6.18-219.el5xen
> /boot/xen-syms-2.6.18-219.el5
> /boot/xen.gz-2.6.18-219.el5 <= 64-bit
> ...
> 
> # rpm -qpl kernel-xen-2.6.18-219.el5.i686.rpm
> /boot/.vmlinuz-2.6.18-219.el5xen.hmac
> /boot/System.map-2.6.18-219.el5xen
> /boot/config-2.6.18-219.el5xen
> /boot/symvers-2.6.18-219.el5xen.gz
> /boot/vmlinuz-2.6.18-219.el5xen
> /boot/xen-syms-2.6.18-219.el5
> /boot/xen.gz-2.6.18-219.el5 <= 32-bit
> ...
> 
> So, it's highly unlikely that either internally to Red Hat,
> or any of our customers, would ever run such a combination.
> And I don't recall ever working with the crash utility to
> support it.
> 
> I'm curious whether anybody on this list has ever done this?
> 
> After all these years of Xen existence, you would think that
> somebody else would have bumped into this anomoly before...
> 
> Dave
> 
> 
> 
> 
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> 
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