Allow the user to select a GICv5 via '-machine gic-version=x-5', and
document this. The 'x-' prefix indicates that the emulation is still
in an "experimental" state as far as QEMU is concerned; the
documentation describes what "experimental" means for the user and
what parts are not yet implemented.
We do not make 'gic-version=max' enable GICv5 here because:
* the GICv5 architectural spec is still at the EAC level and could
have minor changes between now and its final version; only users
who specifically want to start working with the GICv5 should
select it
* QEMU's implementation here is still not fully featured, and
selecting it instead of GICv3 will mean losing functionality such
as MSIs
* the GICv5 is not backwards compatible with the GICv3/GICv4 for
system software, so silently "upgrading" an existing command line
to GICv5 is just going to break existing guest kernels
The last one in particular suggests that even when the emulation
moves out of "experimental" status we will probably not want to
change "max".
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20260327111700.795099-66-peter.maydell@linaro.org
Peter Maydell
b380e88021