Deal with Nvidia legacy support introduced in XLibre Xserver 25.1.0

[callmetango]

Describe the feature

We should somehow deal with the Nvidia legacy support introduced in XLibre Xserver 25.1.0. The changelog says:

In the new 25.1 series, we added optional support for the legacy proprietary Nvidia drivers v340, v370, and v470 too. To generally enable it, you have to pass the legacy_nvidia_padding flag to the Xserver build to re-add a struct field that is long gone. As a consequence, you may need to recompile other XLibre DDX drivers as well. No fear, your distribution of choice will very likely take care of this. For the support of the Nvidia v340 driver, you'll also have to pass the legacy_nvidia_340x build time option, which readds two internal functions used by this driver. Again, these steps are optional and only needed for the legacy Nvidia drivers.

I have been considering how we can deal with this.

1. One possibility would be to hardwire the Nvidia legacy flags legacy_nvidia_padding and legacy_nvidia_340x into the ebuild. This would give us permanent support. The previously compiled drivers would have to be recompiled, but we could enforce that via a new revision of xlibre-drivers and the dependency on all 25.0.x driver versions.

2. Another option would be a use flag such as “nvidia-legacy.” However, I don't yet have any idea how we could then handle the drivers. Ultimately, we would have to recompile them every time the use flag was changed.

3. A third option would be to maintain two parallel ebuilds analogous to the webkit-gtk ebuilds with different revision numbers at the end per ABI. But that sounds kind of strange.

4. A fourth option would be to use the “Multiple ABIs for X.Org” scenario in Sub-slots and Slot-Operators - Gentoo wiki. However, that sounds quite complicated

@stefan11111 What do you think?

It should be done because

Changing the legacy_nvidia_padding of the XLibre Xserver needs a recompilation of the accompanying drivers. If we fail to do so, they may be broken and XLibre won't start.

What are the alternatives?

No response

Additional context

XLibre XServer 25.1 Changes · X11Libre/xserver Wiki

Extra fields

• I have checked the existing issues
• I have read the Contributing Guidelines
• I'd like to work on this issue

[stefan11111]

@callmetango We could also add a masked use flag and an ewarn that drivers should be recompiled.
Since this is gentoo, we could also just do nothing. Users can add this build option themselves in MYMESONARGS.

Probably the best way is to add a masked use flag with an ewarn, and delete all drivers on toggle, like we do when the package gets uninstalled, but I'm not sure if ebuilds support this.

[hendrack]

Imho an ewarn is enough.

Can portage show that when the normal nvidia USE flag is set? Edit: Nvm I forgot there is no global nvidia USE flag.

Maybe add an eselect news item to the repo with more detailed instructions?

[stefan11111]

@callmetango ping

[stefan11111]

@callmetango ping

[callmetango]

Yes, I copied and will work in this today.