Black Screen Crash at Boot

[MCNPathfinder]

Good afternoon!

I've been running Proxmox for probably a little more than a year now. It's been pretty stable as long as I don't mess with it. Well... I messed with it. I was attempting to get my 4 port NIC pass through to a VM. I was getting an error that said something about IOMMU. I double-checked that all of the available virtualization options were turned on in the BIOS. The last ditch effort was to try and follow these instructions: https://forum.proxmox.com/threads/iommu-broke-solved.53188/.

I run an old Dell OptiPlex 755 and it looked like IOMMU shouldn't be a problem. When I did the steps for GRUB and did the "update-grub", Proxmox no longer starts up. It seems like it gets through GRUB, but then stops pretty much right away mentioning something about "Can't process LV pve/vm-100..." and it ends saying something about "/dev/mapper/pve-root: clean..." then switches to a completely black screen. It's outputing black because my monitor self-adjusts and doesn't go to sleep, but there is no hard drive activity, no response from the keyboard, and I have to do a hard shutdown in order to turn off the computer.

I put the Proxmox ISO on a flash drive and I am able to get everything back if I do a "Rescue Boot", but it won't boot on it's own.

Any ideas on what I might have done and how to reverse it?

 

[dcsapak]

The last ditch effort was to try and follow these instructions: https://forum.proxmox.com/threads/iommu-broke-solved.53188/.

what exactly did you try from there?

did you see the official docs? https://pve.proxmox.com/wiki/PCI(e)_Passthrough

I run an old Dell OptiPlex 755 and it looked like IOMMU shouldn't be a problem.

what cpu exactly? from experience, the older the platform cpu, the worse the iommu and vt-d support/implementation
(afaict the cpu is core 2 duo era, so quite old as far as cpus go)

..." then switches to a completely black screen

did you check if the network was working from another pc?

I put the Proxmox ISO on a flash drive and I am able to get everything back if I do a "Rescue Boot", but it won't boot on it's own.

mhmm check the logs (e.g. the messages/syslog/journalctl) from the boot that didnt work

Any ideas on what I might have done and how to reverse it?

i do not know what you have done exactly, but it seems that the activation of the iommu has gone wrong,
so disable that again, (e.g. remove that from /etc/default/grub and run update-grub again)

 

[MCNPathfinder]

Thank you for your reply! I was able to get it back working thanks to your tips! I should've followed the directions from Proxmox instead of what I had found online. I ended up adding a bunch of extra files and folders (due to my misunderstanding of basic CLI commands) and I think this corrupted GRUB when I updated. I thought the boot process had made it past GRUB, but I was incorrect.

Of course I couldn't leave well enough alone, and decided to follow the official Proxmox instructions for passthrough. Same thing happened, but at least I knew what exactly I did and how to reverse it.

Long story short, it's back up and running! Just how I left it before I started mucking around. Thank you thank you thank you! I guess this machine just doesn't do passthrough... It's also supposed to support 8GB of RAM, but I haven't found anything that works to get it there. Stuck at 7GB,

Might be time for a new server. Thanks again!