How Can I Effectively Debug Core Files from Remote Customer Systems with Differing Linux Distributions?

Debugging Core Files from Remote Customer Systems

Debugging core files from customer systems can be challenging, especially when the software is compiled without debugging symbols. To address this issue, this guide provides insights and resources for effective core file analysis.

Linux Distribution Compatibility

When core files are generated from a different Linux distribution than the development environment, the stack trace may not be meaningful. This is because GDB locates function addresses in the local copy of shared libraries, which may differ from those on the customer system. To obtain an accurate stack trace, obtain copies of the customer's shared libraries and set the "solib-absolute-prefix" to their location in GDB using (gdb) set solib-absolute-prefix /path/to/libraries.

Recommended Books for Linux and Solaris Debugging

For advanced Linux and Solaris debugging, consider the following books:

• "The Practice of System and Network Administration" by Thomas Limoncelli, Christina Hogan, and Strata R. Chalup
• "Debugging with GDB: The GNU Source-Level Debugger" by Richard Stallman and Roland H. Pesch
• "Solaris Performance and Troubleshooting" by Richard W. Jardine and Gildas C. Cator

These books provide real-life debugging scenarios, advanced techniques, and assembly-level debugging guidance.

Analyzing a Sample Crash

Consider the following example crash:

Program terminated with signal 11, Segmentation fault.
#0  0xffffe410 in __kernel_vsyscall ()
(gdb) where
#0  0xffffe410 in __kernel_vsyscall ()
#1  0x00454ff1 in select () from /lib/libc.so.6
...
<omitted frames>

For a meaningful stack trace, obtain the libc.so.6 library from the customer system and set the prefix path in GDB. Then, issue the (gdb) where command to display the corrected stack.

Alternative Approach to Shipping Debuggable Binaries

Instead of distributing -g binaries to customers, consider the following approach:

• Compile with both -g and -O2 and output the debuggable binary as myexe.dbg.
• Strip the debugging symbols to create myexe.
• Distribute myexe to customers.
• Use myexe.dbg for debugging core files from customers.

This method provides symbolic information for debugging without exposing source details or shipping a separate debuggable binary.

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