Messages in this thread | | | Subject | Re: [RFC 0/5] kernel: backtrace unwind support | From | Peter Zijlstra <> | Date | Fri, 10 Feb 2012 18:43:15 +0100 |
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On Fri, 2012-02-10 at 12:25 +0100, Jiri Olsa wrote: > I was recently dealing with libunwind and wanted to try out > the dwarf backtrace unwind in kernel space. > > The attached patchset implements dwarf backtrace unwind > based on the exception header frames (.eh_frame_hdr and > .eh_frame ELF sections). The code is mostly stolen from > libunwind (git://git.sv.gnu.org/libunwind.git). > > I'm not sure how much of usage this can be given that we > already have quite reliable stack backtrace, and given > the complexity of the dwarf unwind. But I might be > overlooking something and this could be of use for someone > else. > > Also it needs to be said, that the state of this patchset > is far from being done. It's in state 'working for me' on > x86_64 and seems to provide reliable backtrace. > > attached patches: > - 1/5 unwind, kconfig: Adding UNWIND* options > - 2/5 unwind, x86: Generate exception frames data for UNWIND_EH_FRAME option > - 3/5 unwind, dwarf: Add dwarf unwind support > - 4/5 unwind, api: Add unwind interface and implementation for x86_64 > - 5/5 unwind, test: Add backtrace unwind test code
Right, so last time someone did a x86 dwarf unwinder there was a bit of a 'discussion' and Linus basically told people to go away. That said, there are a number of literate dwarfs in various architectures because that simply the only way to get a backtrace on them.
So I CC'ed Linus who has a strong here, jejb since he's the one that told me several time there's a number of literate dwarfs already in the kernel and Jan because I think it was him that tried last on x86.
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