I'm not sure if this is an issue already reported with CM4, but it seems different, and I'm wondering if there's anything I can do to debug it. I really want recent Windows on arm64 + PCI, so the CM4+IO setup would be perfect for me.

I'm using the "lite" variant of the CM4 board with no on-board emmc, so everything boots from the external SD.

In my first attempts to run the install, I thought everything was just hung on the raspberry pi logo with the boot process dots at the bottom. Eventually I saw on a YouTube video this can take a long time, so I left it for 30+ minutes (didn't see any spinning dots, just the static boot logo). Certainly more than 10 minutes in the FAQ. Lo and behold, the installer came up and ran to completion. Amazing.

However, on subsequent boots I get a blue-screen-boot-loop, with on the generic report of "WHEA UNCORRECTABLE ERROR" but no specifics. I tried enabling the UEFI output and error over UART, but that didn't seem to output anything. When I break to a UEFI prompt I don't see anything interesting on the fs0: drive in terms of logs.

I saw in one comment that this might be to do with the difference between rpi4 and cm4 with the PCI/USB-3 config, and an off-hand reference to a branch to tweak it, but the trail went cold there.

Is there any way I can get more diagnostics as to how windows failed? Or are there some specific pointers to experimental branches I might be able to try? Or could this be another issue, like my use of SD card for install, and I should try an M.2 NVME device?