Hello misc@, I’m trying to boot OpenBSD (current) on iMac Pro (iMacPro1,1). It’s Apple’s Xeon-W based PC with ECC memory.
This machine is very picky when it comes to OS support. Obviously macOS is well supported and I don’t have problems with it, MS Windows on an external USB drive is stable as well. I tried whole BSD family, multiple Linux based distros and Illumos. The only Linux distribution I was able to boot and install was Clear Linux* - ended up with kernel panicking randomly, and regarding BSDs - I was able to install and boot FreeBSD but it randomly fails with a Machine Check Exceptions. The other interesting thing is infamous T2 chip in which iMac Pro is equipped - almost every crash ends up with BridgeOS crash report. I would consider OpenBSD assertion failures and FreeBSD MCA errors "UNCORR PCC GCACHE L2 ERR error" as valid if it wasn’t for rock stable macOS and MS Windows (and on both it’s pushed hard at times, for a few hours straight, incl. VMs). And my understanding is that this iMac Pro is no exception - other iMacs present similar behaviour (ending up with similar T2 chip Bridge OS crash reports). I tried to do my homework and installed OpenBSD on an external USB drive via VMWare Fusion and built kernel with DEBUG flag. External USB drive is the only option because of T2 chip. Tried to boot .SP kernel, tried to disable some devices - though probably doesn’t matter because I assume it’s crashing before autoconf is even involved. I also, tried to update microcode at boot on FreeBSD - someone suggested that via Twitter - didn’t help for at runtime MCA faults (CPU had most recent microcode). OpenBSD snapshot fails with: "fatal machine check in supervisor mode" "panic: trap type 18, code=0, pc=…" https://www.dropbox.com/s/birtxskxayjvxht/OpenBSD%20default%20kernel.jpeg?dl=0 The only mention I found regarding this issue and potential solution - other than replacing potentially faulty CPU - was to turn off the BIOS option “Page directory cache”, for “older Linux kernels”: https://virtuallyfun.com/wordpress/2009/09/01/openbsd-amd64-fun/ But there is no standard BIOS or anything similar on this Apple PC. Debug kernel fails with something similar to: "kernel: machine check trap, code=0" "Stopped at uvm_pmr_assertvalid+0xd6: testq %rsi,%rsi" https://www.dropbox.com/s/08nvew3ajk5cs7e/OpenBSD%20DEBUG%20kernel.jpeg?dl=0 Other crashes (from different tries): https://www.dropbox.com/s/di4dbeju0uwyfvt/Crash%20default.jpeg?dl=0 https://www.dropbox.com/s/5pkf64afjnixv1b/Crash%20DEBUG.jpeg?dl=0 https://www.dropbox.com/s/q0dieiwkisj1ilr/Crash%20default%202.png?dl=0 PC reboots soon after (USB keyboard doesn’t work anyway). FreeBSD MSA crash: https://www.dropbox.com/s/66dmjjqhbwyd194/FreeBSD%20MCA.jpeg?dl=0 After a few weeks of throwing different OpenBSD kernels, BSD, Linux based distributions at this iMac I decided to post here, maybe someone would have an idea how to improve OpenBSD experience on this machine. ;) I understand that I just may be doomed and have to accept facts - either it’s broken by design or faulty CPU must be replaced, and it’s just a hobby project - especially I’d like to play/learn more about arm/arm64 boards and OpenBSD - but if there is even a slight chance to boot it on iMac… Thank you for any hint, Krystian I wasn't sure how I could share images, decided to use Dropbox.
