Re: [patch 0/3, nios2] unbreak nios2-linux-gnu GDB

Sandra Loosemore
2015-04-28T15:10:07Z

On 04/28/2015 04:59 AM, Yao Qi wrote:
> Sandra Loosemore <sandra@codesourcery.com> writes:
>
>> GDB support for nios2-linux-gnu became broken during the time when
>> glibc and kernel support for that target was transitioning to the
>> upstream repositories. Both ports were accepted around the first of
>> the year, but then the initial 3.19 kernel was not usable for testing
>> due to some unrelated problems with the ethernet support, it took a
>> long time to track down a bug that caused a kernel hang, and then we
>> ran into some additional bugs with kernel cache flushing. The icache
>> flush issues were fixed in time for the 4.0 kernel release and GDB is
>> working pretty well with that kernel version now for manual use, but
>> to get consistent results from automated testing I had to apply an
>> additional local patch to flush the dcache more aggressively. I
>> expect some version of that will make it into future kernel releases
>> since Altera is aware of the trouble now.
>
> In short, with your patches applied, GDB/GDBserver should work well with
> kernel 4.0 release (with your local patch to flush dcache), is it a
> correct statement?

Yes. GDB works well for ordinary manual debugging even without the
dcache fix kernel patch (I couldn't reproduce the random failures I saw
in automated testing by hand).

> Do you have a GDB test summary (number of PASS and
> FAIL) to show how well it does now?

Sure. This is from dropping mainline GDB into a 2015.05 CodeBench build
(GCC 4.9.2, glibc 2.21):

# of expected passes 19447
# of unexpected failures 105
# of unexpected successes 1
# of expected failures 31
# of known failures 69
# of unresolved testcases 1
# of untested testcases 67
# of unsupported tests 269

....which is a big improvement over the status quo of not being usable
at all. :-)

-Sandra