[Crash-utility] Need help to get crash to work on kdump geneatedvmcore

[Dave Anderson]

"Sampathkumar, Kishore (STSD)" wrote:

>  Hi,I have been working on back-porting kexec/kdump functionality from 2.6.13 vanilla kernel to RHEL4, Update 2 kernel
> (version 2.6.9-22).As part of that, when I try to invoke "crash" on a vmcore generated, I get the following error in
> "crash" tool:[root crash-4.0-2.23]# ./crash /boot/System.map-2.6.9-kdump-1
> /usr/src/redhat/BUILD/kernel-2.6.9-kdump-1/linux- 2.6.9/vmlinux /root/vmcore crash 4.0-2.23
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> This GDB was configured as "x86_64-unknown-linux-gnu"... crash: read error: kernel virtual address: ffffffff813a8200
> type: "xtime"[root crash-4.0-2.23]# [root crash-4.0-2.23]# I tried with both crash-4.0-2.15 as well as crash-4.0-2.23.
> Same result.- Should I be re-building crash as part of the back-port?- Is crash capable of handing vmcore's generated
> by kdump?- Can someone suggest how I can make progress to get crash to work for this?Thanks,- Kishore
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Hi Sampathkumar,

First thing, presuming that the vmlinux file is associated with the vmcore
file, take the System-map argument out of the picture -- i.e, invoke the
session as:

 $ crash -d7 vmlinux vmcore

the -d7 will display a bunch of debug data.

What looks unusual is the ffffffff813a8200 address for "xtime".  That
would seem to be too high -- except perhaps if the vmlinux you're working
against (or maybe the unnecessary System-map) is the kdump kernel loaded
at 16MB?

If you do this, the output should show the exact same kernels:

 $ strings vmcore | grep "Linux version"

 $ strings vmlinux | grep "Linux version"

Dave


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