On Fri, Oct 12, 2018 at 02:33:26PM -0700, Jeff McGee wrote:
> On Fri, Oct 12, 2018 at 01:51:46PM -0700, Rodrigo Vivi wrote:
> > On Fri, Oct 12, 2018 at 01:24:30PM -0700, Jeff McGee wrote:
> > > The GuC firmware team is proposing a change to the firmware versioning scheme.
> > > The goal is to more accurately track the firmware interface to help users
> > > manage dependencies on that interface. The proposed scheme is based on
> > > semver.org with some additions to handle branching.
> > >
> > > The proposed version number would have 4 fields: BASE.MAJOR.MINOR.PATCH.
> > > Contrast this with the 2 fields in the current version number: MAJOR.MINOR.
> > > Side note, the current firmware encodes a BRANCH and CLIENT number as well, but
> > > they have not been needed by i915. So a firmware released with the proposed
> > > scheme would be named <platform>_guc_ver<base>_<major>_<minor>_<patch>.bin
> > > (ex: skl_guc_ver1_5_4_7.bin) instead of the current
> > > <platform>_guc_ver<major>_<minor>.bin (ex: skl_guc_ver9_33.bin).
> > >
> > > The BASE number is an ID that is used to identify a set of releases in which
> > > the MAJOR.MINOR.PATCH semantics are consistent. In other words, two releases
> > > from the same BASE can be compared via their MAJOR.MINOR.PATCH to infer their
> > > relationship as described below. Two releases from a different BASE cannot be
> > > reliably compared. The BASE number facilitates arbitrary branching which can
> > > create duplicate and/or disconnected MAJOR.MINOR.PATCH versions. This type of
> > > branching is expected to be rare, and so BASE will rarely change. When a new
> > > BASE is created, the MAJOR.MINOR.PATCH reset to starting values.
> >
> > Could you please clarify a bit what BASE means?
> > What would be a different BASE?
> >
>
> The BASE number supports general branching that would cause version number
> conflicts. Branching for firmware releases is not desirable, but it is a
> practical reality. Therefore the versioning scheme must accomodate it. Let's
> say that a high-priority request is made to put specific updates on an old
> release that said customer is locked on. Those updates could include any sort
> of change including interface change. Then we have a sequence like below:
>
> v1.1.0.0 v1.1.0.1 v1.1.0.2 v1.1.0.3 v1.1.1.0
> ----O----------O----------O----------O----------O
> \
> \
> \
> O----------O
> v2.1.1.0 v2.1.1.1
>
> You can see that if we don't have a BASE number that changes from 1 to 2, then
> we end up with duplicated v1.1.0 along the different branches which are not the
> same. As I wrote, this should be a very rare scenario, but it can happen. Maybe
> upstream will always be supplied with releases from the "main" BASE, and you
> can ignore this field, but it needs to be there for other firmware
> distributions.
> -Jeff
>
Sorry, I misrepresented how to the numbers would change in the above example.
The change of BASE from 1 to 2 would reset MAJOR.MINOR.PATCH. So the sequence
should be v1.1.0.2 -> v2.1.0.0 -> v2.1.0.1 and so on.
If we don't have BASE, the pure semver.org sequence would be:
v1.0.0 v1.0.1 v1.0.2 v1.0.3 v1.1.0
----O----------O----------O----------O----------O
\
\
\
O----------O
v1.1.0 v1.1.1
And so you see the duplication of version number.
- Jeff
> > >
> > > The MAJOR number conforms to the major in semver.org. It increments on a
> > > backwards incompatible change of the interface. It resets to 1 on a change of
> > > BASE. The MAJOR number basically works the same between the current and
> > > proposed versioning schemes.
> > >
> > > The MINOR number conforms to the minor in semver.org. It increments on a
> > > backwards compatible change of the interface (new interfaces that are optional
> > > to use). It will also increment on substantial new internal functionality that
> > > doesn't affect the interface but should be called out to the user. It resets to
> > > 0 on a change of MAJOR. The MINOR number in the current versioning scheme
> > > increments on any backwards compatible change. The proposed versioning scheme
> > > breaks this into the MINOR number just described and the PATCH number below.
> > >
> > > The PATCH number conforms to the patch in semver.org. It increments on a
> > > backwards compatible internal change, usually a bug fix. It resets to 0 on a
> > > change of MINOR.
> >
> > I like the idea of MAJOR.MINOR.PATCH following semver.org.
> >
> > I think if we remove the BASE out of picture and just use semver clear,
> > but maybe it is just because I didn't quite understand BASE.
> >
> > >
> > > The MAJOR.MINOR collectively define the interface version. Because the MINOR
> > > may also increment on a substantial internal change, it doesn't always mark an
> > > interface change, e.g. 4.5 and 4.6 may have identical interfaces. But the
> > > determination of interface compatibility is unchanged, e.g. 4.6 is always
> > > backwards compatible with 4.5.
> > >
> > > Each MAJOR.MINOR may continue to receive internal fixes along a branch even
> > > after the main branch for that BASE has moved on to another MAJOR.MINOR.
> > > Releases from these fix-only branches increment only the PATCH number on that
> > > MAJOR.MINOR, and therefore remain semantically consistent with the main branch.
> > > No change of BASE is therefore needed. Consider an example:
> > >
> > > v1.1.0.0 v1.1.0.1 v1.1.0.2 v1.1.1.0 v1.1.1.1
> > > ----O----------O----------O----------O----------O <-- main adopts v1.1.1.x
> > > \
> > > \
> > > \
> > > O----------O <-- fixes for interface v1.1.0.x
> > > v1.1.0.3 v1.1.0.4
> >
> > This approach is cool and more or less how Mesa handles their releases,
> > except by the fact that their Major is the year and minor is the month.
> >
> > However, on the firmware side I have a concern because we are so far trying
> > to make sure that we have 1-1 relationship on kernel-firmware version.
> >
> > But based on this view and what Anusha told me yesterday it seems
> > that GuC is getting constant releases. With the constant patches we will
> > soon explode linux-firmware.git repository size.
> >
> > But this maybe is something to be solved on linux-firmware side and we make
> > sure that we clean up and remove firmware that were never released in any
> > official Linux kernel. Anusha or Antonio, thoughts?
> >
> > Thanks,
> > Rodrigo.
> >
>
> I expect that i915 will still require a single version of firmware per platform
> as it does today. This change should not impact that other than to require i915
> to check 4 numbers instead of 2.
>
> It is true that firmware releases are made *internally* (from the firmware
> team to the operating system teams) at a frequent rate. It is up to each OS
> team to decide their own cadence for integrating and distributing those
> firmware based on their unique situation. So the Linux team may filter these
> releases and update the upstream much less frequently.
>
> > >
> > > There is no need to change the BASE because the branching happened from the
> > > last fix (v1.1.0.2) on the main branch prior to the change of interface
> > > (v1.1.1.0). As long as only fixes are applied to v1.1.0.x, there is no risk of
> > > version number clash. All of these release versions remain semantically
> > > connected with one small caveat. If this set of release versions came
> > > sequentially along a single branch, one could infer that the exact fixes in
> > > v1.1.0.4 were inherited by v1.1.1.0. With this "hidden" branching, this may
> > > not be true as in this example. One would need to review the v1.1.1.0 release
> > > notes to check.
> > >
> > > Please provide any feedback on the proposed change.
> > >
> > > Thanks,
> > > Jeff
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
