[PATCH] docs: driver-api: firmware: add driver firmware guidelines.

[Pierre-Louis Bossart]

On 7/18/22 19:29, Dave Airlie wrote:
>>> +* Firmware should be versioned with at least a major/minor version. It
>>> +  is suggested that the firmware files in linux-firmware be named with
>>> +  some device specific name, and just the major version. The
>>> +  major/minor/patch versions should be stored in a header in the
>>> +  firmware file for the driver to detect any non-ABI fixes/issues. The
>>> +  firmware files in linux-firmware should be overwritten with the newest
>>> +  compatible major version. Newer major version firmware should remain
>>> +  compatible with all kernels that load that major number.
>>
>> would symbolic links be acceptable in the linux-firmware.git where
>> the <fmw>_<major>.bin is a sym link to <fwm>_<major>.<minor>.bin
>>
>> or having the <fwm>_<major>.bin really to be the overwritten every minor
>> update?
> 
> I don't think providing multiple minor versions of fw in
> linux-firmware is that interesting.
> Like if the major is the same, surely you always want the newer ones.
> As long as the
> ABI doesn't break. Otherwise we are just wasting disk space with fws
> nobody will be using.

It was my understanding that once a firmware file is in linux-firmware
it's there forever. There are tons of existing symlinks to point to the
latest version, but the previous versions are not removed/overwritten.

see random examples:
ls -lR /lib/firmware  | grep t4fw
ls -lR /lib/firmware  | grep fw_release