Re: GDB 13 release -- 2023-01-21 Update

[Luis Machado <luis.machado@arm.com>]

On 1/29/23 11:52, Joel Brobecker wrote:
>>>>>      - With that said, the patch appears to simply add a cache,
>>>>>        so the logic of it all doesn't appear to be extremely
>>>>>        complicated. So I would rate the risk to be low.
>>>>
>>>> That's what it seems to me.
>>>>
>>>> I think another round of testing would be a good step to make sure there are no hidden bugs.
>>> My understanding is that the problem was making debugging borderline
>>> impossible.  Or at least, really, really unpleasant.  So I think it
>>> qualifies as a bug fix, and that the benefit is worth the risk.
>>
>> Right. Past a short number of frames, unwinding got really really slow.
> 
> The part that I haven't been clear on is whether this affected everyone
> on Arm-32bit, or everyone on both Arm and AArch64, or just a subset
> of the users?

Just a subset.

It affects 32-bit m-profile Arm targets that report the additional stack pointers.  This is either
the org.gnu.gdb.arm.m-system feature or the org.gnu.gdb.arm.secext feature.

I'm fairly sure these features are only reported by emulators and bare-metal targets.

Now, a 64-bit gdb can debug 32-bit Arm as well, so you could have a 64-bit gdb running into this too
if the target is a 32-bit m-profile Arm. But the target is still 32-bit Arm.

This doesn't affect AArch64 at all.

> 
> Regardless of the above, I agree we can backport. To avoid confusion,
> can I leave this to you, Luis, to confirm that the two patches I identified
> previously are the only two patches that need to be backported, and
> can you backport those for us, with a round of testing if you haven't
> done so already, just to double-check?

Sure. I gave it a try with master and the test results look the same with or without the patches.

Unfortunately the 32-bit Arm test results are not too clean as there is quite a bit of noise from
failing watchpoints tests.

I'll try with GDB 13 just to be sure.

> 
> For the record, those patches were:
> 
>      commit d72ba177c85f2ad18d0dcabdd8844532c9acb819
>      Author: Torbj�rn SVENSSON <torbjorn.svensson@foss.st.com>
>      Date:   Thu Nov 17 12:17:53 2022 +0100
>      Subject: gdb: dwarf2 generic implementation for caching function data
> 
> ... and ...
> 
>      commit 5cf11483141a58314834653003e49709b47822d5
>      Author: Torbj�rn SVENSSON <torbjorn.svensson@foss.st.com>
>      Date:   Thu Nov 17 12:18:20 2022 +0100
>      Subject: gdb/arm: Use new dwarf2 function cache
> 
> Thank you!