With the Ryzen 9 7900X, an Asus B650E series motherboard, and 32 GiB DDR5, the results I've gotten aren't favorable. I was able to install xcp-ng-8.3.testing-2023.02.15-12.19-install.iso without enabling x2API in the BIOS, and XCP-ng comes up fine. While xo-ce (running on the same box) comes up right away, it takes about 8-10 minutes before it acquires it's IP address (both XCP-ng and xo-ce use DHCP to get their IPs from a DHCP/DNS).
After xo-ce is up and accessible, Windows 10 works well (install from ISO, boot & run performance is good). OSs from various Linux distros are horrendously slow. It took about 2 hrs to install Linux Mint 21.1 from an ISO. It takes several minutes, with any of the Linux ISOs I've tried (CentOS Stream 9.1, Ubuntu 22.04.1, Linux Mint 21.1) for a 2nd screen to appear after the initial install screen (which comes up fine).
The install of Mint took about 2 hrs to complete.
VM configuration: 8-CPUs, 8 GiB RAM, 22 GiB hard drive.
Linux Mint OS comes up, but with similar slow boot time (29 minutes before LM logo, CPU usage at 100% on Stats tab during that 29 minutes, but oddly everything else at 0. Then I noticed CPU usage dropped and both Network and Disk throughput had activity, but still 0B of 8GiB RAM used, and I switched tabs and these 2 messages appear in the console screen:
1. [ 1.778229] vbd vbd-5696: 19 xenbus_dev_probe on device/vbd/5696
2. [165.437239] piix4_smbus 0000:00:01.3: SMBus Host Controller not enabled!).
(LM logo appeared on the console window shortly after the 2 messages above)
At 48 minutes (per the VM_Started time on the Logs tab) the arrowhead cursor first appeared (console window), and the login screen appeared at 52 minutes. At 57 minutes the desktop is displayed (still at 0 GiB RAM usage) and system response is extremely slow.
Another Note - these messages appeared on the xo-ce console window:
[ 3684.425914] rcu: INFO: rcu_sched self-detected stall on CPU
[ 3684.425914] rcu: #1-...!: (1 ticks this GP) idle=d22/0/0x1 softirq=3206/3206 fqs=1
[ 3684.425914] rcu: rcu_sched thread starved for 4463 jiffies! g321 f0x0 RCU_GP_WAIT_FQS(5) -> state=0X402 ->cpu=1
[ 3684.425914] rcu: #unless rcu_sched thread gets sufficient CPU time, OOM is now expected behavior.
[ 3684.425914] rcu: RCU grace-period kthread stack dump:
{Nothing after that on the screen}
Side Note: my original Intel XCP-ng box shows all 4 (CPU, Memory, Network and Disk all peaking roughly at the same time that the Linux Mint OS boots, but on this new Ryzen box, 0B Memory at all times on the Stats screen for the Linux Mint VM. The xo-ce VM does show about 712 MiB Memory usage.
I did try a separate boot, with X2API enabled in the motherboard BIOS before booting XCP-ng, but it didn't make any noticeable difference compared to having it set to Default.
Repeating: I didn't experience sluggishness, problems installing, booting or running Windows 10 from an ISO under XCP-ng on this Ryzen box, only Linux distros.
Far Side Notes: I used the same Linux Mint 21.1 ISO from above and installed it directly on a separate hard drive on the same Ryzen box and it works good. I'm running VMware running under Linux Mint 21.1 and Rocky Linux 9 loaded directly on this Ryzen box on separate hard drives and VMware works good when I boot on those drives (XCP-ng/xo-ce is running on a Samsung 970 plus M.2).
I hope some of the information will be useful to the XCP-ng development team.
I'd be glad to test a fix on my Ryzen box if that would help.
It's a home lab box, so starting over isn't an issue.
I'm fairly new to XCP-ng. I'm impressed by the support of the XCP-ng team for home users too.
Addendum - inside the Linux Mint VM, I entered the free command in a terminal window.
Results:
total used free shared buff/cache available
Mem: 8119596 727396 6087584 20004 1304616 7103828
Swap: 1043340 0 1043340