While at it, I have a concern about the compat mode: profiling an ARMv7 binary on an ARMv8 system. Is this supported by libdw? I know you can do it with libunwind by linking multiple libraries, cf. [1]. However this is utterly complex to implement.
[1] http://www.nongnu.org/libunwind/man/libunwind%283%29.html#section_4 , cf. 'Cross-platform and Multi-platform Unwinding'. Regards, Jean On 26 February 2014 09:15, Jean Pihet <[email protected]> wrote: > Hi Mark, > > On 26 February 2014 00:26, Mark Wielaard <[email protected]> wrote: >> Hi Jean, >> >> Seems you already got your answer to the build question solved. > Yes! There is quite a huge improvement in performance: >500% for dwarf > unwinding ;-p > >> >> On Tue, 2014-02-25 at 18:17 +0100, Jean Pihet wrote: >>> The goal is to add the libdw support for perf on ARM (and later AARCH64). >> >> Note that there is some code in elfutils git that handles .debug_frame >> for ARM, but not yet code for handling EXIDX tables. For non-debug >> unwinding ARM uses EXIDX tables, not .eh_frames. Handling EXIDX tables >> is probably easiest done by translating them to CFI. In case you want to >> do unwinding using libdw without .debug_frame available. > That is good to know. Our use cases suppose we have the .debug_frame > section in the binaries by default and otherwise the frame pointer can > be used. > >> For AARCH64 there is some code available on my branch: >> https://git.fedorahosted.org/cgit/elfutils.git/log/?h=mjw/aarch64-unwind >> Which might or might not work. I need to get access again to a aarch64 >> setup to do some more testing before moving this to master. > Great! AARCH64 is next on my plate, I surely will let you know the status. > > Thx for you replies! > Jean > >> >> Cheers, >> >> Mark >>
