gdb reverse debugging error

Question

Hi,

i started to try reverse debugging with gdb 7, followin the tutorial:

http://www.sourceware.org/gdb/wiki/ProcessRecord/Tutorial

and I thought, great!

Then I started to debug a real program which gives an error at the end. So I run it with gdb, and I put a breakpoint just before the place I think the error appears. Then I type "record" in order to start to recrd actions for future reverse-debugging. But after some steps I get

Process record doesn't support instruction 0xf0d at address 0x2aaaab4c4b4e.
Process record: failed to record execution log.

Program received signal SIGTRAP, Trace/breakpoint trap.
0x00002aaaab4c4b4e in memcpy () from /lib64/libc.so.6
(gdb) n
Single stepping until exit from function memcpy,
which has no line number information.
Process record doesn't support instruction 0xf0d at address 0x2aaaab4c4b4e.
Process record: failed to record execution log.

Program received signal SIGABRT, Aborted.
0x00002aaaab4c4b4e in memcpy () from /lib64/libc.so.6

Before I look at in in detail, I wonder if this feature is still buggy, or if I should start to record from the beginning.

Where this "record" error happens, just an object is created as a copy of other:

Thanks

Answer 1

Sounds like precord is still buggy.

Please make sure you are using the latest released GDB 7.1, and file a bug. Output from x/i 0x2aaaab4c4b4e will likely be helpful. So will be exact distribution and versions of GCC and libc.so.6

Answer 2

This is because this insn is still not support by prec.

It is fixed now. You can try the gdb-cvs-head.