I’ll answer quickly and “messily” as I’ve no time now, but I’ll develop more tomorrow if you need/want.
My working Xen setup is :
- BIOS boot on a MSI B350 PC-Mate, Ryzen 1700x 8c/16t
- AMD RX580 on the primary/x16 PCIe slot → PT to my gaming win7 HVM domU. I modprobe-blacklist the amdgpu driver, and tell in xorg.conf to only use the nvidia card. The GPU does not support FLReset, but I found ways to make it work, ie. I can reboot w7 w/o rebooting dom0
- nvidia GT710 on a PCIe x1 slot (the small ones) → for dom0 GUI
- the 2nd “GPU/PCIe x8 slot” (the one meant for SLI/crossfire) is occupied by a 10GbE NIC to connect to my backup dom0
- both GPUs are connected to my 3 screens
- Xen on debian stable, no libvirt. Using XFCE as dom0 GUI
- working HVM domUs with Seabios, I never used OVMF/UEFI : Debians, pfsense (as a global dom0/domU fw, with MoBo NIC PT), TrueNAS core (freeBSD-based, with a NVMe optane PT), w7 (GPU+audio+USB controller: all PT), openBSD, Solaris 11.3, a nested Xen-on-Debian, and even … a nested Qubes \o/
Everything is flawless, maybe I’m just lucky with HW choices, or HW+SW combo.
On boot, the AMD GPU displays the BIOS, then GRUB, then some part of VT1 logs, then it automagically swaps the display to the nVidia GPU for the rest of VT1 logs (hence the display gets frozen on the AMD-connected screens from now on, till I PT it to w7 or another U), then it displays X.
Considering the “from Xen to Qubes” doc, I was talking about the Qubes documentation only.
For the Xen docs: I recently joined the Debian-Xen team because I wanted to help them - and thank them - and from there I learnt there’s a new guy responsible for the rework of the Xen docs (he’s working at Vates, creators of XCP-ng/XenOrchestra). I contacted him and I’m heavily pushing for the docs to be up-to-date really quickly. But will I succeed, it’s another story !
But I feel you, my first experiences with Xen were exactly as you said, painful : “googling and reading documentation, wikis, reddit posts, forum posts, random blog posts, and other sites, Virtualization doc, specifically for Xen”. There’s no easy way.
For Xen, I find the best ressource is the man pages on “Xen Documentation”. You read the wiki pages for general pointers/guidance, then check the last edit date on the bottom of the page, then read the man pages to adapt to the recent way of doing stuff.
Also, I found the documentation from XCP-ng may be of help sometimes, for anything not too related to XAPI stuff. Also the virt guide from Suse.
You can also mimick KVM/libvirt config stuff to Xen.
More later ^^ Don’t give up !