Nouveau X.Org Driver To Drop Maxwell & GLAMOR Support

[phoronix]

Phoronix: Nouveau X.Org Driver To Drop Maxwell & GLAMOR Support

Patches are pending to remove GLAMOR support from the xf86-video-nouveau DDX driver and as a result to also drop the Maxwell hardware support...

http://www.phoronix.com/scan.php?page=news_item&px=Nouveau-Drop-GLAMOR-Max

[blackout23]

I thought Xwayland needs GLAMOR if you want hardware acceleration. So performance of Xwayland will be poor for people using nouveau since it's offloaded to the CPU?

https://plus.google.com/+KristianH%C3%B8gsberg/posts/Nrcu655dd4F

[imirkin]

I thought Xwayland needs GLAMOR if you want hardware acceleration. So performance of Xwayland will be poor for people using nouveau since it's offloaded to the CPU?

Xwayland does indeed need GLAMOR. What it doesn't need is the nouveau (or any other) ddx.

As usual, this article misses (or ignores) a few key bits of information:

(a) the GLAMOR integration in nouveau is completely broken. I have no interest in fixing it, but it's causing me to have to deal with users coming in with issues brought on by it. Removing seemed like the obvious choice.
(b) A DDX like nouveau (or ati, or intel) has very little benefit from having a GLAMOR integration over the modesetting driver, which also has a GLAMOR integration. Users will get a much better experience with modesetting + GLAMOR than nouveau + broken GLAMOR integration.

All that said, there appear to be some mesa driver bugs which cause GLAMOR issues with either integration. Maxwell support is in the very early stages, and not really being worked on due to lack of interest.

Mario did point out a few things that were missing in the modesetting DDX, so I may consider leaving it in, at least until the EXA impl is done (which has been at the 99% point for the past 6 months or so).

[AnAkIn]

Xwayland does indeed need GLAMOR. What it doesn't need is the nouveau (or any other) ddx.

As usual, this article misses (or ignores) a few key bits of information:

(a) the GLAMOR integration in nouveau is completely broken. I have no interest in fixing it, but it's causing me to have to deal with users coming in with issues brought on by it. Removing seemed like the obvious choice.
(b) A DDX like nouveau (or ati, or intel) has very little benefit from having a GLAMOR integration over the modesetting driver, which also has a GLAMOR integration. Users will get a much better experience with modesetting + GLAMOR than nouveau + broken GLAMOR integration.

All that said, there appear to be some mesa driver bugs which cause GLAMOR issues with either integration. Maxwell support is in the very early stages, and not really being worked on due to lack of interest.

Mario did point out a few things that were missing in the modesetting DDX, so I may consider leaving it in, at least until the EXA impl is done (which has been at the 99% point for the past 6 months or so).

Since there is a move towards wayland, is there any point to still work on EXA rather than making all video cards use glamor from the modesetting driver, when possible ?

[imirkin]

Since there is a move towards wayland, is there any point to still work on EXA rather than making all video cards use glamor from the modesetting driver, when possible ?

I'm unaware of any such move (at least on any of my systems). The EXA code was easy to do, so why not. There's just one mildly tricky part, which is why it's stuck at the 99% mark. If you're interested in improving the GLAMOR situation, feel free to work on that.

Also note that not all NVIDIA GPUs will be able to run GLAMOR... certainly G80 and up can, but older ones may have a harder time (not to say anything of their fixed-function hardware like TNT(2) and GF1/2/3/4).

[bridgman]

Since there is a move towards wayland, is there any point to still work on EXA rather than making all video cards use glamor from the modesetting driver, when possible ?

I read this as "keep the Nouveau DDX around for parts which already have EXA acceleration, use modesetting/glamor for newer parts", not doing any further work on EXA.

[patrakov]

Ilya,

at XDC 2014, we talked about a bug exposed by Thunderbird, and you (or maybe some other Nouveau developer) told me that it matched a privately-reported EXA bug. I was told to use this (working) workaround in order to avoid corruption while scrolling:

Option "WrappedFB" "true"

I have not tested whether this EXA bug is fixed (and cannot test until tomorrow). So, what's the plan with it? During the conference, I got the impression that nobody cares to fix it, because everybody is waiting for GLAMOR to become mature enough to displace EXA, and now you come with this statement about older cards that will never support GLAMOR. Yes, I understand that it doesn't apply to my card (NVIDIA Corporation GF108M [GeForce GT 425M] [10de:0df0] (rev a1)), but still.

[ssokolow]

Xwayland does indeed need GLAMOR. What it doesn't need is the nouveau (or any other) ddx.

As usual, this article misses (or ignores) a few key bits of information:

(a) the GLAMOR integration in nouveau is completely broken. I have no interest in fixing it, but it's causing me to have to deal with users coming in with issues brought on by it. Removing seemed like the obvious choice.
(b) A DDX like nouveau (or ati, or intel) has very little benefit from having a GLAMOR integration over the modesetting driver, which also has a GLAMOR integration. Users will get a much better experience with modesetting + GLAMOR than nouveau + broken GLAMOR integration.

All that said, there appear to be some mesa driver bugs which cause GLAMOR issues with either integration. Maxwell support is in the very early stages, and not really being worked on due to lack of interest.

Mario did point out a few things that were missing in the modesetting DDX, so I may consider leaving it in, at least until the EXA impl is done (which has been at the 99% point for the past 6 months or so).

Would you mind clarifying what this means for potential future open-source driver support for people with GTX750 cards like mine?

[imirkin]

Would you mind clarifying what this means for potential future open-source driver support for people with GTX750 cards like mine?

Business as usual. Instead of having

Driver "nouveau"

in your xorg.conf, you instead have

Driver "modesetting"

Or if you're wise enough to not have a device section in the first place, everything will Just Work (tm).

[imirkin]

Ilya,

at XDC 2014, we talked about a bug exposed by Thunderbird, and you (or maybe some other Nouveau developer) told me that it matched a privately-reported EXA bug. I was told to use this (working) workaround in order to avoid corruption while scrolling:

Option "WrappedFB" "true"

I have not tested whether this EXA bug is fixed (and cannot test until tomorrow). So, what's the plan with it? During the conference, I got the impression that nobody cares to fix it, because everybody is waiting for GLAMOR to become mature enough to displace EXA, and now you come with this statement about older cards that will never support GLAMOR. Yes, I understand that it doesn't apply to my card (NVIDIA Corporation GF108M [GeForce GT 425M] [10de:0df0] (rev a1)), but still.

I've never been to XDC, so probably not me. This is the first I'm hearing of this (or I heard of it then promptly forgot). I'm not sure what WrappedFB does... presumably something like ShadowFB? Which is horrible. I'll suggest that these forums are not the proper place for bug reports.

As for GLAMOR, Wayland, etc -- it is my opinion that Wayland won't be a thing I care about for another 5-10 years. Using GLAMOR on top of nouveau (drm driver) is going to be disastrous for all parties involved as it will reveal a ton of issues in context switching etc. I already semi-ignore issues brought on by gnome-shell & co usage, this will just push that set of issues on everyone since GLAMOR will effectively trigger the same types of problems. The manpower (and/or interest) is plain not there to deal with such a deluge.

Note that this is just my opinion, and I'm moderately sure that everyone else feels like EXA is pass? and GLAMOR is the future and Wayland is going to take over the world real soon now. But I don't share in that vision. I see EXA as a very well-tested proven-stable path, separate from mesa (and thus not dependent on various upgrades/etc) and am unaware of any issues in X for non-crazy setups.