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

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

On Sun, Apr 12, 2020 at 07:48:19PM +0200, Bengt Richter wrote:
> Could it be segfaulting trying to access a missing v86d ?

The code for loading the uvesafb module looks like this:

(invoke #+(file-append kmod "/bin/modprobe")
        "uvesafb"
        (string-append "v86d=" #$v86d "/sbin/v86d")
        "mode_option=1024x768"))))

So it should call

modprobe uvesafb v86d=/gnu/store/…-v86d-…/sbin/v86d mode_option=1024x768

and it should be impossible for v86d to be missing.  On x86_64 and
i686 at least, and on other architectures uvesafb will not be loaded.

Then again, if the GUI works because of other drivers already, we need
not fix it, I think.  Also I still believe the error comes because
other drivers already reserve needed memory -- passing nomodeset
should make sure they don’t.  Except if vesafb or xf86-video-vesa is
loaded, which is not the case in the installer.

Regards,
Florian