[Crash-utility] Error when running crash utility - crash: read error: kernel virtual address: c1399f10 type: "xtime"

Tue Aug 11 23:44:15 UTC 2009

Hello Dave,

Thanks for the mail. It helped a lot.

This is what I did:
I installed the latest version of Crash.

The parameters are as assigned:
CONFIG_PHYSICAL_START=0x1000000
CONFIG_PHYSICAL_ALIGN=0x400000

So now I ran the command as
crash --readnow --reloc=12m /usr/src/linux-2.6.25.14-main/vmlinux
/var/crash/2009-08-08-23:32/vmcore
and got the output properly.

Thanks once again.

Regards,
Mani

On Tue, Aug 11, 2009 at 5:10 PM, Dave Anderson <anderson at redhat.com> wrote:

>
> ----- "Mani" <mani2885 at gmail.com> wrote:
>
> > Hello,
> >
> > I am trying to analyse the dump created by the kdump utility. This is
> what I did
> > I took 2.6.25.14 vanilla version of kernel and made two copies of the
> > kernel named vmlinuz-2.6.25.14-main (Production kernel) and
> > vmlinuz-2.6.25.14-kdump (Crash kernel) by following the procedure
> > mentioned in the following website
> > http://www.dedoimedo.com/computers/kdump.html
> >
> > When I run crash utility using the following command
> > crash /usr/src/linux-2.6.25.14-main/vmlinux
> /var/crash/2009-08-08-23:32/vmcore
> >
> > I get the following error
> >
> > crash /usr/src/linux-2.6.25.14-main/vmlinux
> /var/crash/2009-08-08-23:32/vmcore
> >
> > crash 4.0-6.0.5
> > Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008 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.
> >
> > 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 "i686-pc-linux-gnu"...
> >
> > crash: read error: kernel virtual address: c1399f10 type: "xtime"
> >
> >
> > I checked for the error and found this link which mentions few
> > work-around/fixes for the issue with reading of /dev/mem
> > http://www.mail-archive.com/crash-utility@redhat.com/msg01553.html
>
> Alright -- before even talking about the "xtime" read error above --
> you've gone off into the weeds...
>
> The CONFIG_STRICT_DEVMEM issue only applies to analyzing the *live* system
> with the crash utility, so it's completely irrelevant to your attempt
> to analyze a kdump vmcore.
>
> And with respect to CONFIG_STRICT_DEVMEM, you want to *avoid* building
> your kernel with it if you want to look at the live system with crash.
> If you *add* CONFIG_STRICT_DEVMEM, then you have to work around its
> disabling of the usage of /dev/mem.  One of the ways to do that is
> to try the kretprobe hack.  Other than that, you'd have to port the
> Red Hat "/dev/crash" driver to your kernel for live system analysis.
>
> So -- don't do this:
>
> > I tried adding CONFIG_STRICT_DEVMEM to the .config file (This
> > parameter was not already present in the config file)
> > I got the following error while compiling the kernel
> >
> > scripts/kconfig/mconf arch/x86/Kconfig
> > .config:3869:warning: trying to assign nonexistent symbol STRICT_DEVMEM
> >
> > I tried to create the kretprobe module, it works fine for do_fork()
> > but when I give devmem_is_allowed() as the functioin name I get the
> > following error
>
> and if you don't build your kernel with CONFIG_STRICT_DEVMEM to begin with,
> then there's no need to do this:
>
> > [root at buzzsaw kprobes]# insmod kretprobe_devmem.ko
> > insmod: error inserting 'kretprobe_devmem.ko': -1 Operation not
> > permitted
>
> In any case, I don't know why the insmod is failing unless you're trying to
> do it as a non-root user.
>
> > I am new to the area of kernel debugging. Please let me know how I can
> > solve this issue. Thanks
>
> Getting back to the original "xtime" read error issue, I don't
> know what's causing it off-hand.  Here's what I can suggest:
>
> (1) Update your version of the crash utility.  4.0-8.11 is available
>    on the upstream site at http://people.redhat.com/anderson.  The
>    easiest way to go is to take the tar.gz file there, un-tar it, go
>    into the resultant directory, and type "make".  The crash binary
>    will be built into that top-level directory.
> (2) Indicate what your kernel's CONFIG_PHYSICAL_START and
> CONFIG_PHYSICAL_ALIGN
>    config options are equal to.  It's possible that you may be running into
>    http://people.redhat.com/anderson/crash.changelog.html#4_0_4_5
> (3) If that version does not work, then post the output of
>    "crash -d7 your-vmlinux your-vmcore", and we can go from there.
>
> Thanks,
>  Dave
>
> --
> Crash-utility mailing list
> Crash-utility at redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility
>

-- 
Regards,
Mani
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