Am 02.06.21 um 10:57
schrieb Daniel Stone:
> Hi Christian,
>
> On Tue, 1 Jun 2021 at 13:51, Christian König
> <ckoenig.leichtzumerken@gmail.com>
wrote:
>> Am 01.06.21 um 14:30 schrieb Daniel Vetter:
>>> If you want to enable this use-case with driver
magic and without the
>>> compositor being aware of what's going on, the
solution is EGLStreams.
>>> Not sure we want to go there, but it's
definitely a lot more feasible
>>> than trying to stuff eglstreams semantics into
dma-buf implicit
>>> fencing support in a desperate attempt to not
change compositors.
>> Well not changing compositors is certainly not
something I would try
>> with this use case.
>>
>> Not changing compositors is more like ok we have
Ubuntu 20.04 and need
>> to support that we the newest hardware generation.
> Serious question, have you talked to Canonical?
>
> I mean there's a hell of a lot of effort being expended
here, but it
> seems to all be predicated on the assumption that
Ubuntu's LTS
> HWE/backport policy is totally immutable, and that we
might need to
> make the kernel do backflips to work around that. But
... is it? Has
> anyone actually asked them how they feel about this?
This was merely an example. What I wanted to say is that we
need to
support system already deployed.
In other words our customers won't accept that they need to
replace the
compositor just because they switch to a new hardware
generation.
> I mean, my answer to the first email is 'no, absolutely
not' from the
> technical perspective (the initial proposal totally
breaks current and
> future userspace), from a design perspective (it breaks
a lot of
> usecases which aren't single-vendor GPU+display+codec,
or aren't just
> a simple desktop), and from a sustainability
perspective (cutting
> Android adrift again isn't acceptable collateral damage
to make it
> easier to backport things to last year's Ubuntu
release).
>
> But then again, I don't even know what I'm NAKing here
... ? The
> original email just lists a proposal to break a ton of
things, with
> proposed replacements which aren't technically viable,
and it's not
> clear why? Can we please have some more details and
some reasoning
> behind them?
>
> I don't mind that userspace (compositor, protocols,
clients like Mesa
> as well as codec APIs) need to do a lot of work to
support the new
> model. I do really care though that the
hard-binary-switch model works
> fine enough for AMD but totally breaks heterogeneous
systems and makes
> it impossible for userspace to do the right thing.
Well how the handling for new Android, distributions etc...
is going to
look like is a completely different story.
And I completely agree with both Daniel Vetter and you that
we need to
keep this in mind when designing the compatibility with
older software.
For Android I'm really not sure what to do. In general
Android is
already trying to do the right thing by using explicit sync,
the problem
is that this is build around the idea that this explicit
sync is
syncfile kernel based.
Either we need to change Android and come up with something
that works
with user fences as well or we somehow invent a
compatibility layer for
syncfile as well.
What's the issue with syncfiles that syncobjs don't suffer
from?