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 <[email protected]> wrote: > > ----- "Mani" <[email protected]> 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/[email protected]/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: > > > [r...@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 > [email protected] > https://www.redhat.com/mailman/listinfo/crash-utility > -- Regards, Mani
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