bug#40538: installer: Support uvesafb to install on machines without KMS.

[pelzflorian (Florian Pelz)]

uvesafb should be run in the Guix System installer image so the GUI
installer can be used on more systems, including AMD GPU systems.

uvesafb is needed to support systems that otherwise need nonfree
firmware or drivers (many current and older AMD GPUs as well as old
machines like Uniwill U50SI1 with Silicon Integrated Systems GPU). I
attach a patch I made previously at
<https://lists.gnu.org/archive/html/guix-patches/2020-04/msg00226.html>
(plus proper indentation and copyright statement).  I believe it could
be included in the installer even though it is a little hacky.

Note that the installed system will need uvesafb (or nonfree firmware)
too, so the patch alone won’t make these systems work out of the box.
But these things are easier to setup when the system can be installed
via the GUI installer.  I wrote the same about the issue previously at
<https://lists.gnu.org/archive/html/guix-devel/2020-03/msg00350.html>.


On some machines uvesafb still requires to add a kernel parameter
nomodeset (or sometimes possibly vga=793 or something; nomodeset was
enough on tested machines, some machines don’t need nomodeset).

In my testing so far uvesafb did not cause any trouble on systems that
don’t need it.  I have not tested non-x86 systems and just hope the
code won’t break those.


When the dust has settled on the kernel-module-configuration-service
discussed by Brice Waegeneire and Danny Milosavljevic
<https://lists.gnu.org/archive/html/guix-patches/2020-04/msg00272.html>,
a proper uvesafb service can be added.  Then I can make and test one
and it could also be used in the installer.  That would be the clean
solution.  In particular, it could detect the resolution to use for
uvesafb automatically by running the attached code testvbe.scm as
root.  But how to run that code depends on the
kernel-module-configuration-service if/when it exists.  (I did not
know how to extend etc-service-type with a file created at runtime not
build time, but maybe kernel-module-configuration-service works
differently anyway.)

On Fri, Apr 10, 2020 at 12:38:05PM +0200, Ludovic Courtès wrote:
<https://lists.gnu.org/archive/html/guix-devel/2020-04/msg00187.html>
> "pelzflorian (Florian Pelz)" <address@hidden> skribis:
> > On an Acer Aspire 5738PG with ATI Mobility Radeon HD 4570 the
> > installer remains black.  I pressed ctrl-alt-f3 and typed
> >
> > modprobe uvesafb v86d=$(guix build v86d | head -n1)/sbin/v86d 
> > mode_option=1024x768
> 
> Could we come up with a udev rule or a modprobe.d snippet so that this
> happens automatically?
> 
> I found things like:
> 
>   https://bbs.archlinux.org/viewtopic.php?id=165480
> 
> Or should we give up on v86d like Gentoo:
> 
>   https://wiki.gentoo.org/wiki/Uvesafb
> 
> ?
> 
> (Perhaps this is best discussed in a specific issue on bug-guix.)

I believe uvesafb can easily be supported on Guix System via
kernel-module-loader-service/configuration-service.

Regards,
Florian

0001-installer-Load-uvesafb-kernel-module.patch
Description: Text document

testvbe.scm
Description: Lotus Screencam