[ltt-dev] ltt buffers from kernel memory dump extractor

Maxim Uvarov muvarov at gmail.com
Thu Aug 19 12:53:50 EDT 2010


There is a tool to extract LTT buffers from kernel dump.  The general
propose of it is to have flight recorder on linux box.
So that you can run LTT in overwrite mode to keep track about all
system or program events in cycling buffer.  When you will get kernel
panic it will be possible to analyze which events were in the system
before crash.

I tried to write it with minimal requirements to external
applications. The latest gdb has so named python macro. So this is
only one single requirement.

Tar ball with sources is attached.

How to use:
1. Compile kernel with:
     - kdump support  - refer to Documentation/kdump documentation.
     - ltt with CONFIG_LTT_VMCORE option.
     - debug info is needed to read information from kernel dump.

2. Run LTT in flight recorder mode with -o channel.all.overwrite=1 option.
lttctl -C -w /root/trace1 trace1 -o channel.all.overwrite=1

3.  Get kernel dump from /proc/vmcore and place it in directory with
ltt.py and .gdbinit.

4. Compile helper function, run make.

5.  Get buffers from vmcore and save that to file:
gdb vmlinux vmcore
> lttsavebuffers
Directory with trace name will appear (trace1).

6.  Apply lttvmcore.patch  patch to ltt viewer lttvmcore.patch

7. Show trace:
lttv  -m textDump -t ./trace1

Best regards,
Maxim Uvarov
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