Messages in this thread | | | Date | Mon, 11 May 2015 11:50:52 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v3 3/3] perf probe: Show better error message when failed to find variable |
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* He Kuang <hekuang@huawei.com> wrote:
> Hi, Ingo > > On 2015/5/11 17:30, Ingo Molnar wrote: > >* He Kuang <hekuang@huawei.com> wrote: > > > >>Indicate to check variable location range in error message when we got > >>failed to find the variable. > >> > >>Before this patch: > >> > >> $ perf probe --add 'generic_perform_write+118 bytes' > >> Failed to find the location of bytes at this address. > >> Perhaps, it has been optimized out. > >> Error: Failed to add events. > >> > >>After this patch: > >> $ perf probe --add 'generic_perform_write+118 bytes' > >> Failed to find the location of bytes at this address. > >What does this sentence mean? I thought 'address' means 'location of > >bytes'. So the address identifies the location and obviously we know > >that. So this message wants to say something else. > > 'generic_perform_write' is a function name, while 'bytes' is a local > variable in this function. Maybe the variable I chose make you confused. > > This maybe clear: > Failed to find the location of 'bytes' at this address.
Yeah, absolutely! This highlights the importance of putting user-supplied symbols into quotes and such.
Maybe even write:
Failed to find the location of the 'bytes' variable at this address.
Another question: what does 'generic_perform_write+118' mean here? Why the offset?
Thanks,
Ingo
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