I have managed to obtain traces using GDB tracepoints in a remote debugging session as explained in this and this other question. I am able to see the frames correctly, as well as the arguments, locals and so on. Then I export the traces to a trace file (tsave command) for further offline analysis as follows:
gdb -q trace_test
Reading symbols from trace_test...
(gdb) target remote :1234
(gdb) trace 3
Tracepoint 1 at 0x555555555157: file /home/juangburgos/Documents/REPOS/trace_test/main.cpp, line 3.
(gdb) trace 8
Tracepoint 2 at 0x555555555184: file /home/juangburgos/Documents/REPOS/trace_test/main.cpp, line 8.
(gdb) b 9
Breakpoint 3 at 0x55555555519a: file /home/juangburgos/Documents/REPOS/trace_test/main.cpp, line 9.
(gdb) actions 1
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect $regs,$args,$locals,$_ret,$trace_timestamp
>end
(gdb) tstart
(gdb) c
Continuing.
Breakpoint 3, main () at /home/juangburgos/Documents/REPOS/trace_test/main.cpp:9
9 return 0;
(gdb) tstop
(gdb) tfind start
Found trace frame 0, tracepoint 1
#0 foo (a=33, b=4) at /home/juangburgos/Documents/REPOS/trace_test/main.cpp:3
3 return a + b + b;
(gdb) tsave /home/juangburgos/Documents/REPOS/build-trace_test-Desktop-Debug/trace02.tfile
Trace data saved to file '/home/juangburgos/Documents/REPOS/build-trace_test-Desktop-Debug/trace02.tfile'.
(gdb) q
The problem now is when I load the trace file in another offline GDB session, then the frames, args, locals are not displayed, only showing ??:
gdb -q trace_test
Reading symbols from trace_test...
(gdb) target tfile /home/juangburgos/Documents/REPOS/build-trace_test-Desktop-Debug/trace02.tfile
Tracepoint 1 at 0x1157: file /home/juangburgos/Documents/REPOS/trace_test/main.cpp, line 3.
Created tracepoint 1 for target's tracepoint 1 at 0x555555555157.
Tracepoint 2 at 0x1184: file /home/juangburgos/Documents/REPOS/trace_test/main.cpp, line 8.
Created tracepoint 2 for target's tracepoint 2 at 0x555555555184.
(gdb) tfind start
Found trace frame 0, tracepoint 1
#0 0x0000555555555157 in ?? ()
Anybody knows what could be causing it? I know it is supposed to work, since that is the defining use case for trace files.
Pay attention to this part of the message that GDB is outputting:
Tracepoint 1 at 0x1157: file ... Created tracepoint 1 for target's tracepoint 1 at 0x555555555157.
It appears GDB is not able to translate the memory offsets from the trace file (0x555555555157) into the memory offset of the loaded image (0x1157).
Try to load the symbols with an offset that matches the difference that is observed.
I.e. 0x555555555157 - 0x1157 = 0x555555554000, then execute:
add-symbol-file ./trace_test -o 0x555555554000
And try tfind start again.