Messages in this thread | | | Date | Wed, 26 Aug 2015 10:32:35 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 2/2] perf probe: Support probing at absolute address |
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Em Wed, Aug 26, 2015 at 09:19:27PM +0800, Wangnan (F) escreveu: > On 2015/8/26 21:02, acme@kernel.org wrote: > >Em Wed, Aug 26, 2015 at 10:38:18AM +0800, Wangnan (F) escreveu: > >>On 2015/8/26 8:02, 平松雅巳 / HIRAMATU,MASAMI wrote: > >>>>From: Wang Nan [mailto:wangnan0@huawei.com] > >>>> # perf probe /lib/x86_64-linux-gnu/libc-2.19.so +0xeb860 > >>>Why do we need "+" for the absolute address? > >>>It seems that we can do it if we find that the given probe point > >>>starts with "0x".
> >>I will change 2/2 as you suggestion.
> >>However, we can only ensure that in kernel side symbol never leading > >>with '0x'. Although I don't think symbol leading with 0x is useful, > >>it is still possible for a userspace program compiled and linked by > >>a language other than C produces such symbol. '+' helps us separate > >>address and function name semantically, make us don't rely on assumption > >>on function names. If in future we do meet '0x' symbols, I think we still > >>need the '+' syntax back. But we can do it at that time.
> >Agreed, I also think that using '+' is better, but will not dwell on > >this so as to make progress :-)
> Maybe we should support both of them, making '+0x1234' the core > syntax, and '0x1234' style as a syntax sugar. However I have worked > on this problem for nearly a full day but my main work should be BPF > related things...
> Since Masami has acked all of the 6 v3 patches, if we still need '+' I can > bring it back with a new patch when I have time. However, same to you, > I don't think this should be a blocking problem.
Agreed, we don't have to agree on everything all the time, lets keep Masami happy this time :-)
- Arnaldo
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