No IOMMU detected, please activate it.

[Windows7ge]

Hello, I'm running PROXMOX 7.1-7 on a Intel Xeon platform and I'm attempting to get hardware pass-through working.

I've enabled VT-d in the BIOS.
I've added intel_iommu=on to GRUB_CMDLINE_LINUX_DEFAULT
I've ran proxmox-boot-tool refresh

The system persists in telling me that IOMMU isn't enabled. I actually had this issue occur on another Xeon server of mine and I'm completely lost as to what's causing the problem.

Meanwhile I have an AMD based server and it's happily running many PCI_e devices in a VM on 7.1-4.

Any thoughts? For as much as I don't like picking sides I'd prefer my main hypervisor server to be Intel based but this is a deal breaker.

 

[Stoiko Ivanov]

is 'intel_iommu=on' present in the output of `cat /proc/cmdline`?
* if yes - I would suggest to read through the journal since boot to see for any messages indicating why it could not be activated
* if not - I guess your system is not using ZFS on / and thus you need to run `update-grub` instead of `proxmox-boot-tool refresh`

I hope this helps!

 

[Windows7ge]

is 'intel_iommu=on' present in the output of `cat /proc/cmdline`?
* if yes - I would suggest to read through the journal since boot to see for any messages indicating why it could not be activated
* if not - I guess your system is not using ZFS on / and thus you need to run `update-grub` instead of `proxmox-boot-tool refresh`

I hope this helps!

Looks like the answer is not (output of cat /proc/cmdline):

initrd=\EFI\proxmox\5.13.19-2-pve\initrd.img-5.13.19-2-pve root=ZFS=rpool/ROOT/pve-1 boot=zfs

I am running ZFS on the boot media. I have a ZFS Mirror configured on a pair of SSD's which PROXMOX boots from.

Also if I try to run update-grub anyways (which is what I'm used to) PROXMOX gives me warning messages:

W: This system is booted via proxmox-boot-tool:
W: Executing 'update-grub' directly does not update the correct configs!
W: Running: 'proxmox-boot-tool refresh'

Is there a way to force update-grub?

 

[Stoiko Ivanov]

ok - you're using ZFS on an UEFI system - meaning grub is not used for booting - systemd-boot is used instead
- you need to edit /etc/kernel/cmdline

see the reference documentation on the topic:
https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#sysboot_edit_kernel_cmdline

 

[Windows7ge]

ok - you're using ZFS on an UEFI system - meaning grub is not used for booting - systemd-boot is used instead
- you need to edit /etc/kernel/cmdline

see the reference documentation on the topic:
https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#sysboot_edit_kernel_cmdline

Alright. I removed intel_iommu=on from GRUB.

I added intel_iommu=on to cmdline:

root=ZFS=rpool/ROOT/pve-1 boot=zfs
intel_iommu=on

Ran proxmox-boot-tool refresh

Rebooted the server.

Same error:


Re-checking cat /proc/cmdline:

initrd=\EFI\proxmox\5.13.19-2-pve\initrd.img-5.13.19-2-pve root=ZFS=rpool/ROOT/pve-1 boot=zfs

 

[Stoiko Ivanov]

I added intel_iommu=on to cmdline:

this needs to be on the same line as the rest

root=ZFS=rpool/ROOT/pve-1 boot=zfs  intel_iommu=on

 

[Windows7ge]

this needs to be on the same line as the rest

root=ZFS=rpool/ROOT/pve-1 boot=zfs  intel_iommu=on

It looks like that did it. For both this server and the previous one with the same issue.

I'll run some experiments to really make sure it's working but otherwise it looks like the problem is solved.

I can't explain why but it still feels strange that suddenly there was a switch from /etc/default/grub to /etc/kernel/cmdline after updating the OS despite the fact the old OS setup and the new one are identically ZFS Mirrors.

Just something I'm going to have to remember should I run into this again. Thank you!

 

[Stoiko Ivanov]

I can't explain why but it still feels strange that suddenly there was a switch from /etc/default/grub to /etc/kernel/cmdline after updating the OS despite the fact the old OS setup and the new one are identically ZFS Mirrors.

The change of boot-loaders for ZFS was done quite a while ago (with PVE 5.4 IIRC) - it was necessary since the ZFS implementation in grub does not support newer features - and quite a few users ended up with systems which could not boot

in any case - glad that worked out

 

[theyost]

I had the same problem.... took a while but this fix gave my my IOMMU groups on my Dell Precision Rack 7910.