Subject: Re: bug#35408: External monitor not working with GDM

From: Ludovic Courtès <[email-masked]>
Date: Fri, 26 Apr 2019 10:14:59 +0200

Hi Ben,

Ben Sturmfels <[email-masked]> skribis:

> [   448.627] (II) RADEON: Driver for ATI/AMD Radeon chipsets:

[...]

> [   448.630] (II) [KMS] drm report modesetting isn't supported.
> [   448.630] (EE) open /dev/dri/card0: No such file or directory
> [   448.630] (WW) Falling back to old probe method for modesetting
> [   448.630] (EE) open /dev/dri/card0: No such file or directory
> [   448.630] (II) Loading sub module "fbdevhw"
> [   448.630] (II) LoadModule: "fbdevhw"
> [   448.631] (II) Loading /gnu/store/xxpf6xz7prlwrvvl7sviaxmahsyavx1c-xorg-server-1.20.4/lib/xorg/modules/libfbdevhw.so
> [   448.631] (II) Module fbdevhw: vendor="X.Org Foundation"
> [   448.631] 	compiled for 1.20.4, module version = 0.0.2
> [   448.631] 	ABI class: X.Org Video Driver, version 24.0
> [   448.631] (EE) Unable to find a valid framebuffer device
> [   448.631] (WW) Falling back to old probe method for fbdev
> [   448.631] (II) Loading sub module "fbdevhw"
> [   448.631] (II) LoadModule: "fbdevhw"
> [   448.631] (II) Loading /gnu/store/xxpf6xz7prlwrvvl7sviaxmahsyavx1c-xorg-server-1.20.4/lib/xorg/modules/libfbdevhw.so
> [   448.631] (II) Module fbdevhw: vendor="X.Org Foundation"
> [   448.631] 	compiled for 1.20.4, module version = 0.0.2
> [   448.631] 	ABI class: X.Org Video Driver, version 24.0
> [   448.631] (EE) open /dev/fb0: No such file or directory
> [   448.631] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support
> [   448.631] (EE) Screen 0 deleted because of no matching config section.
> [   448.631] (II) UnloadModule: "radeon"
> [   448.631] (EE) Screen 0 deleted because of no matching config section.
> [   448.631] (II) UnloadModule: "modesetting"
> [   448.631] (EE) Screen 0 deleted because of no matching config section.
> [   448.631] (II) UnloadModule: "fbdev"
> [   448.631] (II) UnloadSubModule: "fbdevhw"
> [   448.631] (II) Loading sub module "vbe"
> [   448.631] (II) LoadModule: "vbe"
> [   448.632] (II) Loading /gnu/store/xxpf6xz7prlwrvvl7sviaxmahsyavx1c-xorg-server-1.20.4/lib/xorg/modules/libvbe.so
> [   448.632] (II) Module vbe: vendor="X.Org Foundation"
> [   448.632] 	compiled for 1.20.4, module version = 1.1.0
> [   448.632] 	ABI class: X.Org Video Driver, version 24.0
> [   448.632] (II) Loading sub module "int10"
> [   448.632] (II) LoadModule: "int10"
> [   448.632] (II) Loading /gnu/store/xxpf6xz7prlwrvvl7sviaxmahsyavx1c-xorg-server-1.20.4/lib/xorg/modules/libint10.so
> [   448.632] (II) Module int10: vendor="X.Org Foundation"
> [   448.632] 	compiled for 1.20.4, module version = 1.0.0
> [   448.632] 	ABI class: X.Org Video Driver, version 24.0
> [   448.632] (II) VESA(0): initializing int10
> [   448.633] (EE) VESA(0): Cannot read int vect
> [   448.633] (II) UnloadModule: "vesa"
> [   448.633] (II) UnloadSubModule: "int10"
> [   448.633] (II) Unloading int10
> [   448.633] (II) UnloadSubModule: "vbe"
> [   448.633] (II) Unloading vbe
> [   448.633] (EE) Screen(s) found, but none have a usable configuration.
> [   448.633] (EE) 
> Fatal server error:
> [   448.633] (EE) no screens found(EE) 
> [   448.633] (EE) 
> Please consult the The X.Org Foundation support 
> 	 at http://wiki.x.org
>  for help. 
> [   448.633] (EE) Please also check the log file at "/var/lib/gdm/.local/share/xorg/Xorg.0.log" for additional information.

It looks like you have an AMD Radeon graphics card, is that right?  Did
you pass “modprobe.blacklist=radeon” on the kernel command line, or
something similar?

Apparently some of these AMD graphics cards are not quite supported by
free software, so that might be the issue here.

Thanks,
Ludo’.