[PATCH] modules/firmware: add a new option to denote a firmware group to choose one.

[Dave Airlie]

On Fri, 21 Apr 2023 at 05:09, Lucas De Marchi <lucas.demarchi at intel.com> wrote:
>
> On Wed, Apr 19, 2023 at 02:36:52PM +1000, Dave Airlie wrote:
> >From: Dave Airlie <airlied at redhat.com>
> >
> >This adds a tag that will go into the module info, only one firmware from
> >the group given needs to be available for this driver to work. This allows
> >dracut to avoid adding in firmware that aren't needed.
> >
> >This just brackets a module list in the modinfo, the modules in the list
> >will get entries in reversed order so the last module in the list is the
> >preferred one.
> >
> >The corresponding dracut code it at:
> >https://github.com/dracutdevs/dracut/pull/2309
>
> it would be good to have the example usage in the commit message here so
> it can be easily checked as reference for other drivers.

Good point.

>
> I don't think we ever had any ordering in modinfo being relevant for
> other things. Considering the use case and that we could also use a
> similar thing for i915 / xe modules wrt to the major version,
> couldn't we do something like below?
>
>         MODULE_FIRMWARE_GROUP("nvidia/ga106/gsp/gsp");
>         MODULE_FIRMWARE("nvidia/ga106/gsp/gsp-5258902.bin");
>         MODULE_FIRMWARE("nvidia/ga106/gsp/gsp-5303002.bin");
>
> so the group is created by startswith() rather than by the order the
> modinfo appears in the elf section. In i915 we'd have:

The way userspace parses these is reverse order, and it doesn't see
the GROUP until after the FIRMWARE, so this can't work, as it already
will have included all the ones below, hence why I bracketed top and
bottom with a group.

>
> MODULE_FIRMWARE_GROUP("i915/tgl_guc")
>
> There is still an order the kernel would probably like: latest version.
> But then it's an order only among things with the same key.

Dave.