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Re: elfutils/libdw ARM compilation (native and cross compile)
- From: Jean Pihet <jean dot pihet at linaro dot org>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Wed, 26 Feb 2014 09:18:44 +0100
- Subject: Re: elfutils/libdw ARM compilation (native and cross compile)
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. . However this is utterly complex
, cf. 'Cross-platform and Multi-platform Unwinding'.
On 26 February 2014 09:15, Jean Pihet <firstname.lastname@example.org> wrote:
> Hi Mark,
> On 26 February 2014 00:26, Mark Wielaard <email@example.com> 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:
>> 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!