[Crash-utility] problems running crash on recent rawhide live kernels

[Dave Anderson]

Jeff Layton wrote:
> On Fri, 07 Dec 2007 14:55:08 -0500
> Dave Anderson <anderson at redhat.com> wrote:
> 
> 
>> > Jeff Layton wrote:
>> > > Relevant packages:
>> > >
>> > >     kernel-2.6.24-0.62.rc3.git5.fc9.x86_64
>> > >     kernel-debuginfo-2.6.24-0.62.rc3.git5.fc9.x86_64
>> > >     crash-4.0-4.10.x86_64
>> > >
>> > > ... the host is a FV xen guest (but that shouldn't matter, should
>> > > it?).
>>
>>To get crash version 4.0-4.11 to run against that particular
>>dumpfile, it needs to know the kernel's "phys_base" relocation
>>value.  And I don't know how (or if it's even possible) to get
>>it from a fully-virtualized Xen guest dumpfile.  However, if
>>you run crash on the live on the kernel that panicked, you can
>>determine it.  So running live on kernel-2.6.24-0.62.rc3.git5.fc9
>>I see:
>>
>>   crash> help -m | grep phys_base
>>                   phys_base: ffffffffff200000
>>   crash>
>>
>>...which in turn can be used as a command line argument for the
>>xendump dumpfile from that kernel.  So taking the sample dumpfile
>>you gave me:
>>
>># crash --machdep phys_base=0xffffffffff200000 vmlinux
>>vmcore-rawhide.xmdump
>>
>>crash 4.0-4.11
>>Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007  Red Hat, Inc.
>>Copyright (C) 2004, 2005, 2006  IBM Corporation
>>Copyright (C) 1999-2006  Hewlett-Packard Co
>>Copyright (C) 2005, 2006  Fujitsu Limited
>>Copyright (C) 2006, 2007  VA Linux Systems Japan K.K.
>>Copyright (C) 2005  NEC Corporation
>>Copyright (C) 1999, 2002, 2007  Silicon Graphics, Inc.
>>Copyright (C) 1999, 2000, 2001, 2002  Mission Critical Linux, Inc.
>>This program is free software, covered by the GNU General Public
>>License, and you are welcome to change it and/or distribute copies of
>>it under certain conditions.  Enter "help copying" to see the
>>conditions. This program has absolutely no warranty.  Enter "help
>>warranty" for details.
>>
>>NOTE: setting phys_base to: 0xffffffffff200000
>>
>>GNU gdb 6.1
>>Copyright 2004 Free Software Foundation, Inc.
>>GDB is free software, covered by the GNU General Public License, and
>>you are welcome to change it and/or distribute copies of it under
>>certain conditions. Type "show copying" to see the conditions.
>>There is absolutely no warranty for GDB.  Type "show warranty" for
>>details. This GDB was configured as "x86_64-unknown-linux-gnu"...
>>
>>       KERNEL: vmlinux
>>     DUMPFILE: vmcore-rawhide.xmdump
>>         CPUS: 1
>>         DATE: Tue Dec  4 15:41:08 2007
>>       UPTIME: 06:10:51
>>LOAD AVERAGE: 0.00, 0.00, 0.00
>>        TASKS: 74
>>     NODENAME: dhcp231-229.rdu.redhat.com
>>      RELEASE: 2.6.24-0.62.rc3.git5.fc9
>>      VERSION: #1 SMP Sat Dec 1 13:59:08 EST 2007
>>      MACHINE: x86_64  (3458 Mhz)
>>       MEMORY: 511.6 MB
>>        PANIC: "SysRq : Trigger a crashdump"
>>          PID: 0
>>      COMMAND: "swapper"
>>         TASK: ffffffff813a1780  [THREAD_INFO: ffffffff81496000]
>>          CPU: 0
>>        STATE: TASK_RUNNING (ACTIVE)
>>
>>crash>
>>
>>Pain in the ass.  But I don't know any better way.
>>
>>Dave
>>
>>
> 
> 
> Sorry for the delayed response. Did you need me to get that info from
> my xen guest so you could use that coredump, or do you have it
> covered? Thanks for fixing up crash, BTW...
> 

No, thanks, I have that dumpfile stashed aside.

The problem is that I don't see how the physical base address
can be calculated with just the vmcore and vmlinux.  When it's
running live, the physical base address can be calculated using
/proc/iomem.  So I downloaded that kernel, ran it live, and that's
where I got the phys_base value of 0xffffffffff200000, which BTW,
is the first kernel in which I've ever seen it as a negative number.

Dave