Bug 715646

Summary:	sci-biology/foldingathome: notify about nvidia-drivers[nvm] for optional runtime CUDA support
Product:	Gentoo Linux	Reporter:	Brendan Shanks <mrpippy>
Component:	Current packages	Assignee:	Gentoo Science Biology related packages <sci-biology>
Status:	CONFIRMED ---
Severity:	normal	CC:	jstein, juippis, sci-biology, soap
Priority:	Normal
Version:	unspecified
Hardware:	AMD64
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---

Description Brendan Shanks 2020-03-31 16:28:54 UTC

foldingathome can use CUDA, but requires at least two manual steps:
- add the foldingathome user to the 'video' group
- build nvidia-drivers with the 'uvm' USE flag

Having the ebuild do these if the 'cuda' USE flag is enabled seems like the best solution to me.

Reproducible: Always

Comment 1 Ian Stakenvicius (RETIRED) gentoo-dev

2020-04-01 05:01:53 UTC

It is a nice idea, however this goes against use flag policy -- since this is a runtime-only config change and foldingathome itself doesn't change on disk, the use of a USE flag to control what is only a runtime dependency is not something acceptable in a gentoo-repo ebuild.

I am however not up to date on the proper method for managing optional runtime-only dependencies and so I will look up what the best method to notify users of this extra requirement would be.

As I recall, as of the latest version, foldingathome is already added to the video group by default though so that part should be addressed.

Comment 2 Joonas Niilola gentoo-dev

2020-04-01 05:44:03 UTC

(In reply to Ian Stakenvicius from comment #1)
> 
> I am however not up to date on the proper method for managing optional
> runtime-only dependencies and so I will look up what the best method to
> notify users of this extra requirement would be.
> 

We use 'optfeature' from eutils.eclass before IUSE_RUNTIME is implemented. optfeature can be used to include a USE flag 

  optfeature "Nvidia's CUDA unit" x11-drivers/nvidia-drivers[uvm]

and it only prints this line if user doesn't have it installed.

Comment 3 Brendan Shanks 2020-04-01 06:04:51 UTC

Ah ok, I see that mentioned at <https://devmanual.gentoo.org/general-concepts/use-flags/index.html>.
I can find a few ebuilds which seem to use USE flags this way though: 'cuda' in sci-misc/boinc, 'opencl' in app-emulation/crossover-bin, 'ffmpeg' or 'pulseaudio' in www-client/firefox-bin.
If not though, a notification would probably be fine.