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

[Peter Maydell]

On Fri, 10 Mar 2023 at 18:00, Fabiano Rosas <farosas@suse.de> wrote:
>
> 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.

But then presumably a pauth-aware GDB won't actually know
the values it needs to be able to convert between with-PAC
and without-PAC addresses for backtracing?

Luis, how is this intended to work? Is there some way the
stub can check with the gdb that's connected whether the
gdb is able to cope with the pauth XML, so it can avoid
sending it to a gdb that is going to crash if it sees it ?

thanks
-- PMM