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Re: userspace probe breakage with gcc 4.8 due to inablility to locate semaphore variable
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: Mayuresh Kulkarni <mkulkarni at kcg dot com>
- Cc: "'systemtap at sourceware dot org'" <systemtap at sourceware dot org>
- Date: Thu, 16 Apr 2015 10:28:58 -0400
- Subject: Re: userspace probe breakage with gcc 4.8 due to inablility to locate semaphore variable
- Authentication-results: sourceware.org; auth=none
- References: <6ffd4403306349259c75f458f6941a53 at CMKWSCTSMAIL02 dot kcg dot com> <fe9fee0f48a741a2badfe5c436c0aef7 at CMKWSCTSMAIL02 dot kcg dot com>
Mayuresh Kulkarni <mkulkarni@kcg.com> writes:
> [...]
> I had a userspace probe (details below) and this worked fine with stap 1.6 and gcc 4.6. After upgrading to gcc 4.8, this has stopped working. (I believe this to be the only change, everything else on the box is the same)
> [...]
> But, stap -g -vvvvv with the following probe fails with failure to find foo_bar_semaphore
If you use relatively recent <sys/sdt.h> with semaphores (i.e., your C
program #defines _SDT_HAS_SEMAPHORES), you also need to run
"/usr/bin/dtrace -G ..." to create an object file that contains that
semaphore. That .o needs to be linked into your executable.
- FChE