Bug#926886: Please mention video->render change in udev.NEWS

[Guido Günther]

Hi,
On Thu, Apr 11, 2019 at 11:27:05PM +0200, Michael Biebl wrote:
> Am 11.04.2019 um 22:47 schrieb Michael Biebl:
> > Am 11.04.19 um 21:46 schrieb Guido Günther:
> 
> >> it took me a while to figure out why rendering got broken in my wayland
> >> compositor. It would be great if the change from video to render group
> >> could be mentioned in udev.NEWS.
> > 
> > That is unexpected.
> > We still apply the uaccess tag for /dev/dri/renderD* so should be
> > accessible to local, active sessions (including a wayland session)
> > 
> 
> Btw, what exactly was the breakage?

Rendering got corrupted since the compositor could not open the render
node but used /dev/card1.

> I assume you worked around that for now by adding your user to group
> render?
> Which wayland compositor is that, btw? How do you start it?

It's a wlroots based compositor started by a systemd unit¹ and the /dev
tmpfs has currently no ACLs (due to
https://github.com/systemd/systemd/issues/9674) so the uaccess rules
don't apply here. So while I think that uaccess is way more common
(otherwise I'd picked up a way higher severity for the bug) changing
groups of devices might merit a clear warning.

Cheers,
 -- Guido


¹ https://source.puri.sm/Librem5/phosh/blob/master/debian/phosh.service