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Re: [PATCH 2/2] Add test for fast tracepoint enable/disable
- From: Yao Qi <qiyaoltc at gmail dot com>
- To: Simon Marchi <simon dot marchi at ericsson dot com>
- Cc: Yao Qi <qiyaoltc at gmail dot com>, <gdb-patches at sourceware dot org>
- Date: Fri, 01 Apr 2016 14:36:34 +0100
- Subject: Re: [PATCH 2/2] Add test for fast tracepoint enable/disable
- Authentication-results: sourceware.org; auth=none
- References: <1459351018-23718-1-git-send-email-simon dot marchi at ericsson dot com> <1459351018-23718-2-git-send-email-simon dot marchi at ericsson dot com> <86k2kirk18 dot fsf at gmail dot com> <56FD65EB dot 4040109 at ericsson dot com>
Simon Marchi <firstname.lastname@example.org> writes:
> Good question. Because the setup for testing fast tracepoints is
> tedious, I always
> use ftrace-lock.exp as a template, because it is relatively short.
> uses gdb_compile_pthreads. I think it makes sense, because the IPA
> starts a helper
> thread with pthread_create.
gdb_compile_pthreads is used in ftrace-lock.exp because ftrace-lock.c is
a multi-threaded program, but ftrace-enable-disable.c isn't. The
program to be tested is running in one thread, and it doesn't have any
interaction with the helper thread.
> Note that it still builds fine with gdb_compile instead of gdb_compile_pthreads,
> probably because libinproctrace.so has a DT_NEEDED for libpthreads.so,
> so it gets
> pulled in. But using gdb_compile_pthreads should add -pthread to the
> CFLAGS, which
> may impact compilation (e.g. choose re-entrant versions of functions).
Using IPA/fast tracepoint shouldn't affect how the program is compiled.
User is writing and debugging a single thread program, and he/she wants
to use fast tracepoint to debug. He/She shouldn't recompile the program
with -lpthreads or -pthreads, what needed here is to let IPA be loaded with
> However, I just noticed that the command line includes -lpthreads
> instead of -pthreads:
> spawn gcc -Wl,--no-as-needed
> -g \
> -lpthread -lm -o \
> I think that to be more "correct", we should try -pthread before -lpthread in
I am not sure, it is a separate issue, this applies to all test cases
compiled with gdb_compile_pthreads.