Hi Pocock, I did the tests with this variant with 4k pages that you entered today. After installing the Kernel, I placed the usual GPU enable file in the usr / share / X11 / xorg.conf folder. The file just to be precise in everything has this content:
# AST2500
Section "Device"
Identifier "GPU0"
"Modesetting" driver
BusID "PCI: 2 @ 5: 0: 0"
VendorName "ASpeed ​​Corporation"
EndSection
# RX5700 XT
Section "Device"
Identifier "GPU1"
Driver "modesetting" # or amdgpu if you have xf86-video-amdgpu installed
BusID "PCI: 3 @ 0: 0: 0"
VendorName "AMD Corporation"
EndSection
# this is absolutely necessary, it tells xorg which GPU to use for the screen
Section "Screen"
Identifier "Screen0"
Device "GPU1"
EndSection
I use it regularly on Fedora too so I don't think there are any variables when working under Xorg.
After this I restart the computer, I start the kernel you posted, when the operating system loads, it first gave me that output that I posted earlier, that error that was seen during loading and consequently it blocked everything, now instead it no longer gives that error output, it also seems to want to activate the Radeon as it does a sort of restart by turning off and restarting, I see it from the Radeon writing that turns off and then after a few seconds it turns on again. It gets to the gray screen that usually appears before the mouse pointer and login but instead of making all these things appear it stays in that screen and everything crashes irreversibly. So unfortunately even if it seems that we have taken a step forward, we still can't get everything to work with the Navi 10. It seems as if that famous bug that continues to persist in the Fedora Kernel from version 5.7 onwards, is also present in this Debian Kernel. I don't know if there are files that the various Kernel of the various distros share in the same way, obviously apart from the GPU drivers, the fact is that even here we have a very similar problem. Having said that I keep pointing out that even when you load this kernel 5.9, during system loading, in the output list that Debian does when it is loading, it always keeps giving me that error of failure to load the Kernel modules. It does this with both the standard 4.19 and this 5.9. I do assume that Debian installed it more than once to always improve installation details, like some options I forgot or whatever, but in general the main installation has always been the standard one that everyone does. I don't know if it's a 10.7 issue or something else, I just know that that output has always been, so there are obvious Kernel problems as a whole on Debian ...