On Wednesday, 13 February 2019, Ilia Mirkin <imir...@alum.mit.edu> wrote:
> On Wed, Feb 13, 2019 at 12:47 PM Elie Tournier <tournier.e...@gmail.com> > wrote: > > > > On Fri, Jan 25, 2019 at 11:52:56AM -0800, Stéphane Marchesin wrote: > > > On Fri, Jan 25, 2019 at 2:25 AM Gert Wollny <gw.foss...@gmail.com> > wrote: > > > > > > > > Am Donnerstag, den 24.01.2019, 22:25 -0800 schrieb Stéphane > Marchesin: > > > > > > > > > > Yes, it's for running virgl on top of GLES. To emulate fp64 in GL > on > > > > > the guest side, we need fp64 on the host... > > > > > > > > BTW: we could also get it emulated from the guest side. When Elie (in > > > > CC) initially proposed the fp64 emulation series it was for r600 and > > > > TGSI was emitted. The created shaders are horribly long and it is > > > > certainly not performant, but if it's just for getting OpenGL 4.0 > > > > exposed it should be good enough. > > > > > > Yes, Ilia suggested this on IRC yesterday. My impression is that not > > > many applications/games need high performance fp64 (it's likely mostly > > > compute stuff, which is not our target). I could be wrong though. If > > > anyone knows differently, please tell us :) > > > > > > > > > > > I'm not sure though how much work it would be to add this to the soft > > > > fp64 as it has now landed for NIR, though. > > > > > > Yes, with virgl not using NIR, I am not sure how much work soft fp64 > > > will require. > > > > I spent a bit of time on the project recently. > > My thinking so far: > > * FP64 is bad . But everyone knows that. :) > > * Using the current soft fp64 require to emulate int64. > > * Soft fp64 and int64 involve function call which is, iiuc, not really > > supported in TGSI. > > * Soft fp64 is tied to NIR. Some pass/hack need to be port to GLSLIR. > > > > So the project will require a lot of work. > > But what's the alternative? Let's say you make a spec to expose > "proper" fp64 in GLES. No one outside mesa will implement this (why > bother). Certainly not the Adreno/Mali proprietary stacks of the > world. I'm not saying that we should get an extension. My point was, it's a lot of work. > > And if you are on a stack that implements this in GLES, you might as > well be using desktop GL anyways... > > So going back to the original -- what use-case are you trying to cover > that's not already covered some other way? iiuc, Stephane want to run GL desktop on top of GLES. In order to expose a bigger version of GL, he need fp64 support. > > -ilia >
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