X11 not working on 11-STABLE with AMDGPU

[Greg V]

On Wed, Aug 1, 2018 at 8:54 PM, Pete Wright <pete at nomadlogic.org> wrote:
> 
> 
> On 8/1/18 10:29 AM, CL Moonriver wrote:
>> The only thing that actually worked for me was the kms module loaded 
>> in rc.conf. Any attempt to configure the display in xorg.conf 
>> resulted in an X server that would not start, but would continue 
>> running for awhile and appear in the process list before it finally 
>> gave up. But again, I must have an older AMD GPU because it uses 
>> the radeonkms driver instead of amdgpu. (It's an AMD A10-7860k with 
>> Radeon R7 graphics)
>> 
>> On another note, I'm using UEFI boot. Based on my limited 
>> understanding, I think that means X is actually using the scfb 
>> driver, which is not ideal from what I understand (no accelerated 
>> graphics). But it works fine for what I do, and it's the only 
>> configuration I could get working.
>> 
> 
> (removing freebsd-stable@ from this thread as this is X specific)
> 
> hrm, booting UEFI should not restrict which Xorg driver is used for 
> graphics.  For example, on my intel i915 systems I boot UEFI and use 
> the modesetting driver once Xorg launches.  The scfb driver does all 
> rendering in software and does not make use of the GPU at all.
> 
> I'm not super familiar with AMD GPU - do you see any lines in your 
> Xorg.0.log referring to errors attempting to load the modesetting 
> driver?  that might be a good place to start looking.

Hi everyone,

Please keep in mind that both radeonkms and amdgpu from drm-*-kmod 
currently conflict with the EFI framebuffer.

https://github.com/FreeBSDDesktop/DEPRECATED-freebsd-base-graphics/issues/170

I currently have hw.syscons.disable=1 in boot/loader.conf to work 
around that.
That knob literally turns the EFI framebuffer off, so in between the 
boot loader screen and the GPU driver loading, there will be garbage on 
screen :) if the driver fails to load, you keep the garbage. If you 
want to debug the driver with this workaround on (read dmesg, try 
loading, etc.) you have to SSH into the box.