From: Simon Marchi <simon.marchi@ericsson.com>
To: Yao Qi <qiyaoltc@gmail.com>
Cc: <gdb-patches@sourceware.org>
Subject: Re: [PATCH 2/2] Add test for fast tracepoint enable/disable
Date: Fri, 01 Apr 2016 14:42:00 -0000 [thread overview]
Message-ID: <56FE88BA.1000103@ericsson.com> (raw)
In-Reply-To: <8637r5qwm5.fsf@gmail.com>
On 16-04-01 09:36 AM, Yao Qi wrote:
> Simon Marchi <simon.marchi@ericsson.com> 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.
>> ftrace-lock.exp
>> 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
> the program.
That totally makes sense, I'll change it to gdb_compile.
>>
>> However, I just noticed that the command line includes -lpthreads
>> instead of -pthreads:
>>
>> spawn gcc -Wl,--no-as-needed
>> /home/emaisin/build/binutils-gdb/gdb/testsuite/../../../../src/binutils-gdb/gdb/testsuite/gdb.trace/ftrace-enable-disable.c
>> \
>> /home/emaisin/build/binutils-gdb/gdb/testsuite/../gdbserver/libinproctrace.so
>> -g \
>> -lpthread -lm -o \
>> /home/emaisin/build/binutils-gdb/gdb/testsuite/outputs/gdb.trace/ftrace-enable-disable/ftrace-enable-disable
>>
>> I think that to be more "correct", we should try -pthread before -lpthread in
>> gdb_compile_pthreads...
>
> I am not sure, it is a separate issue, this applies to all test cases
> compiled with gdb_compile_pthreads.
>
next prev parent reply other threads:[~2016-04-01 14:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-30 15:17 [PATCH 1/2] Fix write endianness/size problem for fast tracepoint enabled flag Simon Marchi
2016-03-30 15:17 ` [PATCH 2/2] Add test for fast tracepoint enable/disable Simon Marchi
2016-03-31 10:58 ` Yao Qi
2016-03-31 18:01 ` Simon Marchi
2016-03-31 18:31 ` Simon Marchi
2016-04-01 13:36 ` Yao Qi
2016-04-01 14:42 ` Simon Marchi [this message]
2016-04-28 15:30 ` Simon Marchi
2016-04-28 16:03 ` Yao Qi
2016-04-28 16:57 ` Simon Marchi
2016-03-31 10:51 ` [PATCH 1/2] Fix write endianness/size problem for fast tracepoint enabled flag Yao Qi
2016-03-31 11:33 ` Pedro Alves
2016-03-31 12:58 ` Yao Qi
2016-03-31 17:45 ` Simon Marchi
2016-05-05 7:58 ` Yao Qi
2016-05-05 13:50 ` Simon Marchi
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