On Thu, 12 Aug 2021 17:45:47 -0500
o1bigtenor via Dng <dng@???> wrote:

> Greetings
>
> I am running a fairly old rig on debian testing with 2 gpus and want
> to run 5 monitors.
> The 5th is hdmi connected and is a 4k monitor with the other 4 all
> being 1920x1080.
> After I installed the 4k monitor I had regular graphics sub-system
> freezes (won't come out of suspend typically) with a normal being a
> system reboot at least once every 24 hours.
> I filed a bug report. Have subsequently unplugged the 4k monitor - -
> - - a lot of headache rebooting and setting up the machine at least
> 1x per day.

Setting up? As in reallocating desktops?

I'd be more inclined to look at HW/Sw problems when you are adding
something like a 4K screen. Is there sufficient ram?
Are you using the same driver for both GPUs?
Under beowulf, I couldn't load both the amdgpu and radeon drivers.
Have you tried the other way around by setting up 4K, then add the
other monitors one by one?

Although they are rare, there are some odd problems affecting
different HW combos under Linux.

I have a problem where my gpu will not boot with two x 2k monitors on
DisplayPort cables. It is actually the amdgpu that stack crashes.

>
> Recommendation is to download and install even a 5.14 (still in beta)
> kernel.
>
> The newest kernel (changed just yesterday) for debian in debian
> experimental is a 5.13.?? version.
>
> Dunno if I want to try a beta kernel (sorta scared to in fact).

IME, the worst that will happen is a entirely black screen; thus ssh
in to inspect or big red button to restart and then VERY Fast on boot
up to intercept the bios(set max timeout prior) to uninstall, or your
grub should give the option to go to a prior boot image. Note, at one
stage it accumulated them, but now it only keeps current and
previous boot image.

> Suggestions from y'all?
> (Y'all, or at least quite a number of you, have a lot more experience
> at this than I do.)
>
> Please advise.

2c above.