Re: kmscon not working on MacBook

["pelzflorian (Florian Pelz)" <pelzflorian@pelzflorian.de>]

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On Thu, Mar 26, 2020 at 03:26:05AM +0100, Bengt Richter wrote:
> On +2020-03-26 00:00:18 +0100, pelzflorian (Florian Pelz) wrote:
> > on one of my computers uvesafb can only be used after „chmmod o+rw
> > /dev/fb0“ which is a security issue, I suppose.
> >
> 
> Are you a member of the video group?

Indeed the issue was that the gdm user was not a member of the video
group.  Thank you!

I have verified the attached patch makes it sufficient to run
`modprobe uvesafb v86d=$(guix build v86d | head -n1)/sbin/v86d
mode_option=1280x800-32` before `herd restart xorg-server` without any
additional chmod.  I will push if nobody objects.

I do however need to remove xf86-video-vesa via
set-xorg-configuration.  Perhaps xf86-video-vesa should not be among
the defaults if uvesafb is to be made a default.  Note that when not
running X as root, xf86-video-vesa does not work anyway.  That’s what
uvesafb is for.

If uvesafb should be made a default, v86d:testvbe could be used to
find a suitable resolution as a mode_option parameter.

However I still do not know how best to modprobe uvesafb
automatically.

Regards,
Florian

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From 419ec6f3866d223b88f195466d3e731090240a2a Mon Sep 17 00:00:00 2001
From: Florian Pelz <pelzflorian@pelzflorian.de>
Date: Thu, 26 Mar 2020 15:19:21 +0100
Subject: [PATCH] services: gdm: Add gdm user to 'video' supplementary group.

See <https://lists.gnu.org/archive/html/guix-devel/2020-03/msg00351.html>.

* gnu/services/xorg.scm (%gdm-accounts): Set supplementary groups.
---
 gnu/services/xorg.scm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gnu/services/xorg.scm b/gnu/services/xorg.scm
index 09379d40c3..d0196a299e 100644
--- a/gnu/services/xorg.scm
+++ b/gnu/services/xorg.scm
@@ -798,6 +798,7 @@ the GNOME desktop environment.")
         (user-account
          (name "gdm")
          (group "gdm")
+         (supplementary-groups '("video"))
          (system? #t)
          (comment "GNOME Display Manager user")
          (home-directory "/var/lib/gdm")
-- 
2.25.1