Fwd: Re: [libunwind] status of x86_64

[Wu Zhou <woodzltc at cn dot ibm dot com>]

Some information about libunwind.  It seems that they are working on  
improving libunwind, in different branches though.  Do we have any  
plan to merge with their changes?  Just be curious.  :-)

----- Forwarded message from arun.sharma@google.com -----
    Date: Wed, 02 Aug 2006 12:23:25 -0700
    From: Arun Sharma <arun.sharma@google.com>
Reply-To: Arun Sharma <arun.sharma@google.com>
 Subject: Re: [libunwind] status of x86_64
      To: George Lowe <george.lowe@yahoo.co.uk>
      Cc: libunwind@napali.hpl.hp.com

George Lowe wrote:
> What is the current state of support for x86_64?
>
> I note that the most recent version is 0.98.5,
> from April 2005.  If I understand correctly,
> some patches for x86_64 have been proposed.
> I have the following additional questions:
>
>   What is the state of these patches?
 >   How are they bundled?
 >   Does one need to apply a series of patches,
 >   or have the patches been collected into one
 >   large patch?

They're currently in this mercurial repository.

http://www.serpentine.com/~arun/
http://www.serpentine.com/~arun/libunwind/releases/libunwind-0.98.6-test1.tar.gz

>   Will these patches be integrated into
>   the libunwind code?

davidm has reviewed most of them. There are a couple that are still
under review.

>   Can the x86_64 version be built as a
>   static library to be used by a program
>   for introspective purposes?

Yes. I would suggest compiling them with libatomic ops, for better
performance.

http://goog-perftools.sourceforge.net/

has a tool called pprof which does basically this.

>   Does the x86_64 version work with statically
>   linked programs?

Not yet. With glibc_2.3.3 we're a step closer (dl_iterate_phdr works for
statically linked programs). But libunwind can't get to the .eh_frame
section needed to get the dwarf unwinding information.

I'm trying to work out an interface with the gcc folks so libunwind can
get to this info.

	-Arun

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----- End forwarded message -----


Regards
- Wu Zhou