h97m-plus weird iommu

[lancethepants]

I have an h97m-plus motherboard with an i7-4790. In the bios I've enabled intel vt-d, but in the proxmox webui it says iommu not detected. However when I boot and see the 1sec proxmox grub menu, I hit e and add "intel_iommu=on iommu=pt", and voila, iommu works, mostly. Both nics on my pci-e dual nic pass through as one unit, and I'm guessing that's expected for this device. Then I have 2x pci (legacy) nics, but I'm only able to get one of those to pass through, maybe because of shared pci bus?

Anyway, so I create /etc/default/grub.d/iommu.cfg with contents

GRUB_CMDLINE_LINUX="$GRUB_CMDLINE_LINUX intel_iommu=on iommu=pt"

I run "update-grub" and I see that in /boot/grub/grub.cfg that my iommu file was added. It comes in after the zfs linux grub command line entry since I'm using zfs if that's relevant.
I reboot and the computer hangs on the "press f2 or del for bios" screen. I turn off and on again and it boots, but no iommu. So I can only get iommu running if I manually add it in grub while htting 'e' when booting. Anything I'm missing?
thanks!

 

[leesteken]

Some Proxmox installations use GRUB, some use systemd-boot (see the manual). What is the output of cat /proc/cmdline and cat /etc/kernel/cmdline?

 

[lancethepants]

Ah, looking at that manual page I am using systemd-boot, I just assumed it to be a themed version of GRUB. Do I then just edit /etc/kernel/cmdline then?

cat /proc/cmdline

initrd=\EFI\proxmox\6.2.16-3-pve\initrd.img-6.2.16-3-pve root=ZFS=rpool/ROOT/pve-1 boot=zfs intel_iommu=on iommu=pt

cat /etc/kernel/cmdline

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

 

[leesteken]

Ah, looking at that manual page I am using systemd-boot, I just assumed it to be a themed version of GRUB. Do I then just edit /etc/kernel/cmdline then?

Yes (see this part of the manual). You might also be interested in this section (but note the mistake there that states that it's only necessary for older kernels).