Kernel Crash Dumps
On 03/03/2011 07:34 PM, Brian Murray wrote:
On Thu, Mar 03, 2011 at 06:26:18PM -0500, Joseph Salisbury wrote:
On 03/03/2011 04:46 PM, Brian Murray wrote:
In reviewing the kernel debugging documentation I came across the
instructions for saving a crash dump for a kernel panic. I tried
following them and I'm unable to generate a crash dump. Additionally,
that page hadn't been touched in quite some time. I've also found a bug
report about another person having an issue getting crash dumps.
So my question is - is there something wrong with the documentation?
the crash dump process? or me?
I was able to generate a crash dump on a desktop running Natty.
How? Your last comment in the bug report mentions intermittent failures
and maxsize is no longer used by apport so that shouldn't have any
effect. I'd really like to get the documentation and or the process
I performed some more testing today on a Natty desktop. I'm able to
generate a crash dump. However, I've been getting intermittent
failures. Like you mention, changing maxsize doesn't seem to help. It
was just a coincidence that crash dump worked for the first time, after
I increased maxsize. In all the failures, the system hangs performing
the following during the dump file creation:
"Copying data : [N%] <- The percentage when the hang happens varies.
I had to perform some steps in addition to what's listed on the
CrashdumpRecipe wiki. To get crash dump working(Although
intermittently), I performed the following:
1. Installed linux-crashdump and kdump-tools.
- Should it be necessary to install kdump-tools? Without kdump-tools,
I see the following in /var/crash/vmcore.log:
"/root/usr/bin/makedumpfile: error while loading shared libraries:
libdw.so.1: cannot open shared object file: No such file or directory"
- I noticed makedumpfile lives in /usr/bin/ and not /root/usr/bin.
- I tried creating a sym link in /root/usr/bin to point to the real
makedumpfile in /usr/bin, but I still got the same error.
- I performed an ldd on makedumpfile in /usr/bin, and all the libraries
- Again, I tried these things before I installed kdump-tools. Once
kdump-tools is installed, the lib load error goes away.
2. I manually created the /var/crash directory.
3. Edited /etc/default/apport; Changed enabled from 0 to 1.
4. Edited /etc/default/kdump-tools:
- Changed USE_KDUMP from 0 to 1.
- Uncommented: #KDUMP_SYSCTL="kernel.panic_on_oops=1"
- Without kdump-tools installed, this file doesn't exist.
5. Edited /etc/default/kexec. Changed LOAD_KEXEC from false to true,
but this didn't seem to make a difference.
6. Removed 'quiet splash' from the boot parameters(So I could see where
it was hanging).
To trigger a panic, I perform:
echo c | sudo tee /proc/sysrq-trigger
I'll keep experimenting, and see if I can provide some more information.
I'll also update the bug with this latest info.
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