Re: [PATCH v2 0/9] Add MTE stubs for aarch64 user mode

["Alex Bennée" <alex.bennee@linaro.org>]

Gustavo Romero <gustavo.romero@linaro.org> writes:

> Hi Alex,
>
> On 6/14/24 12:49 PM, Alex Bennée wrote:
>> Gustavo Romero <gustavo.romero@linaro.org> writes:
>> 
>>> This patchset adds the stubs necessary to support GDB memory tagging
>>> commands on QEMU aarch64 user mode.
>>>
>>> These new stubs handle the qIsAddressTagged, qMemTag, and QMemTag
>>> packets, which allow GDB memory tagging subcommands 'check',
>>> 'print-allocation-tag', and 'set-allocation-tag' to work. The remaining
>>> memory tagging commands ('print-logical-tag' and 'with-logical-tag')
>>> will also work, but they don't rely on any stub because they perform
>>> local operations.
>>>
>>> Since the memory tagging stubs are not common to all architectures, this
>>> patchset also introduces three functions: gdb_extend_qsupported_features,
>>> gdb_extend_query_table, and gdb_extend_set_table. These functions can be
>>> used to extend the target-specific 'qSupported' feature string and the
>>> handlers for the 'q' (query) and 'Q' (set) packets. These new functions
>>> are used to add the MTE stubs for the aarch64 gdbstub.
>>>   Note that this patchset requires a GDB that supports the
>>> qIsAddressTagged packet (recently added to GDB), so the gdbstub MTE
>>> tests introduced by it must be run using GDB's master branch, since the
>>> GDB in the distros hasn't picked up the change yet.
>>>
>>> Once GDB is built and installed locally, the tests can be exercised, for
>>> example, this way:
>>>
>>> make GDB=~/.local/bin/gdb run-tcg-tests-aarch64-linux-user -j 32
>> It looks like there might be some BSD build failures as well:
>>    https://gitlab.com/stsquad/qemu/-/pipelines/1332635371/failures
>
> I fixed the build for the BSD target in v3, however I think that the GDB in
> the test containers need to be bumped to GDB 15 so the MTE tests can pass,
> because support for IsAddressTagged packet is necessary. GDB 15 branch
> is created by it's not released yet, so I don't know to proceed..

Two potential approaches, you could extend the configure segment:

if test -n "$gdb_bin"; then
    gdb_version=$($gdb_bin --version | head -n 1)
    if version_ge ${gdb_version##* } 9.1; then
        gdb_arches=$($python "$source_path/scripts/probe-gdb-support.py" $gdb_bin)
    else
        gdb_bin=""
    fi
fi

and set a variable exported to config-host.mak to then test in the tcg
test makefiles.

Or you could implement a gdb-version-test command in
tests/tcg/Makefile.target which you could use like the existing
cc-test/cc-option commands to extend config-cc.mak and use that to gate
the tests.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro