Re: [PATCH 09/11] tests/tcg: disable pauth for aarch64 gdb tests

[Alex Bennée]

(adding some more gdb types to CC)

Fabiano Rosas <farosas@suse.de> writes:

> Peter Maydell <peter.maydell@linaro.org> writes:
>
>> On Fri, 10 Mar 2023 at 10:31, Alex Bennée <alex.bennee@linaro.org> wrote:
>>>
>>> You need a very new gdb to be able to run with pauth support otherwise
>>> your likely to hit asserts and aborts. Disable pauth for now until we
>>> can properly probe support in gdb.
>>>
>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>
>> If it makes gdb fall over, then shouldn't we be disabling
>> the pauth gdbstub stuff entirely ? Otherwise even if our
>> tests are fine our users will not be...
>>
>
> Have you seem my message on IRC about changing the feature name in the
> XML? I think the issue is that we're putting the .xml in a "namespace"
> where GDB expects to only find stuff which it has code to
> support. Changing from "org.gnu.gdb.aarch64.pauth" to
> "org.qemu.aarch64.pauth" made it stop crashing and I can read the
> registers just fine.

That would work, although I would prefer to probe support so we can use
the official namespace. We went through something similar with SVE
until:

  797920b952 (target/arm: use official org.gnu.gdb.aarch64.sve layout for 
registers)

which required:

  b1863ccc95 (configure: gate our use of GDB to 8.3.1 or above)

Since then we've introduced:

 ./scripts/probe-gdb-support.py

which given the runes to check for pauth support in gdb could expose a
symbol and we get the best of both worlds. Of course if this keeps
happening we could throw up our hands and just use custom XML for all
the extra register sets.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro