CODEWITHSUNDEEP
cdebugginggdbdebianremote-debugging
Gaius
Gaius

Reputation: 2595

How to use tracing in GDB

In the documentation for gdb:

The tracepoint facility is currently available only for remote targets. See section Specifying a Debugging Target. In addition, your remote target must know how to collect trace data. This functionality is implemented in the remote stub; however, none of the stubs distributed with GDB support tracepoints as of this writing.

Emphasis mine. Where can I get such a stub (for C/C++ code compiled with GCC on Debian x86 or x64)? Or how do I go about making one? The documentation on writing stubs only mentions implementing functions to communicate with the serial ports. Thanks!

Upvotes: 6

Views: 4314

Answers (1)

matt
matt

Reputation: 5624

I don't know much about remotes but some targets in gdb now do support tracepoints there is possibly a way to get at this using a 'normal' gdb info or show command, I could not find it. in the output below tracepoints are supported due to the 'supported=1', this may not be limited to the gdb stub, but also the kernel the stub is running on.

$ gdbserver/gdbserver :12345 ~/tests/test &
$ gdb -quiet
(gdb) file ~/tests/test
Reading symbols from /home/ratmice/tests/test...done.
(gdb) target remote :12345
Remote debugging using :12345
Remote debugging from host 127.0.0.1
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x00000035dd600b20 in _start () from /lib64/ld-linux-x86-64.so.2
Created trace state variable $trace_timestamp for target's variable 1.
Missing separate debuginfos, use: debuginfo-install glibc-2.13-2.x86_64
(gdb) interpreter-exec mi2 -trace-status
^done,supported="1",running="0",frames="0",frames-created="0",buffer-size="5242880",buffer-free="5242880",disconnected="0",circular="0"

Upvotes: 2

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