Sorry, it's been far too long; I definitely did have everything working on
MIPS at the time (6-7 years ago).

On Thu, Feb 9, 2017, 8:21 PM Dave Watson <[email protected]> wrote:

> On 02/10/17 01:05 AM, John Knight wrote:
> > Hi Dave,
> >
> > I finally got a few cycles to work on your suggestions for trying to use
> libunwind version 1.1 and 1.0.  I have confirmed that libunwind version 1.1
> also SEGVs when compiled for Mips.  Same as 1.2.
> >
> > As for version 1.0, the source does NOT compile... it fails to compile
> tests/Gperf-simple.c with multiple undefined references to
> _Umips_getcontext.  I have attached an excerpt from make log file for your
> review.
> >
> > I also have one complaint that covers versions 1.1 and 1.2:
> > The file tests/test-coredump-unwind.c fails to compile on our linux
> system (linux 2.6.36)... the issue is that the test relies on the presence
> of execinfo.h, and functions backtrace() and backtrace_symbols_fd().  The
> issue here is that older linux versions do not have execinfo.h, nor do they
> have backtrace() or backtrace_symbols_fd().  If our version of linux had
> these, than I would not be looking to implement backtrace() capability with
> libunwind.  I am not sure I understand why this test uses these, unless to
> compare the output of libunwind to the output of glibc's backtrace()
> capability.  At any rate, we can't use this test and we end up patching the
> libunwind test source, effectively removing the inclusion of execinfo.h and
> the calls to backtrace() and backtrace_symbols() from the source code just
> to get it to compile.  It would be VERY NICE if there was a flag that could
> be set in the Makefile to skip compiling all of the tests.  In our embedded
> environment, the tests are not useful anyhow.
>
> Git master now has a --disable-tests, but alas it just missed inclusion in
> 1.2.  Next release though.
>
> > At this point, I have pretty much determined that libunwind's mips
> implementation is perhaps just a work in progress and not debugged and
> working. This might explain why mips was not listed as a supported
> architecture in the online documentation; I was kinda afraid of this.  As
> for me, I really don't know enough of the mips architecture to provide
> useful help in debugging this, nor do I have much time available for the
> activity.   I can tell you it does not work in your current source base
> (1.2) and also broken in 1.1.  The fact it doesn't compile in 1.0 is also
> pretty telling for that release as well.  Perhaps the contributor of the
> mips code to the libunwind project can help get it to work?  If the issues
> with it cannot be resolved any time soon, I am afraid I may have to find an
> alternative way to implement backtrace on mips... not something I look
> forward to.
>
> I've cc'd a few of the mips committers if they have any suggestions for
> help.
>
> > Thanks for your suggestions and help with this... I will see if I can
> gleen any more info from the SEGV fault, but alas, I don't have a lot of
> hope for this.  I'll see if I can at least determine what function is
> actually causing the SEGV... beyond this, not sure how much more I can do.
>
> If you do get any more info let us know, I'm out of ideas for now though.
>
> Thanks!
>
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