PCI-E Passthrough: No IOMMU Detected.

[Aerialflame7125]

Hello! Fellow newbie here, I was going around trying to make a gaming vm, I put intel_iommu=on to the line i was supposed to in a tutorial, but now when i try to add a pcie device and start, i get the following message: TASK ERROR: cannot prepare PCI pass-through, IOMMU not present. I have followed some other guides on fixing this issue, i ran

dmesg | grep ecap

and got

DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap d2008c20660462 ecap f010da

And got told the "f" in front of "ecap" was that Interrupt remapping was supported, but I don't know what that means. I checked my BIOS and saw that vt technology was enabled, but i had no other settings corosponding to that. I turned on Intel Turbo Mode thinking it would help, but didn't help at all.
My specs:
8 GiB of ram
4 x Intel(R) Core(TM) i5-4460 CPU @ 3.20GHz (1 Socket)
1TB of internal storage
2 External storage adding up to 5-7 TB of storage
and a GeForce GT 720 (I don't even know why I thought this could handle games)

 

[CalebSnell]

What motherboard do you have?
Also check this thread out https://forum.proxmox.com/threads/task-error-iommu-not-present.95274/
Looks like there are quite a few gotchas when setting the intel_iommu=on line.

 

[leesteken]

What it the output of cat /proc/cmdline? Does your motherboard and CPU both support VT-d?

 

[Aerialflame7125]

What it the output of cat /proc/cmdline? Does your motherboard and CPU both support VT-d?

I got BOOT_IMAGE=/boot/vmlinuz-5.15.107-2-pve root=/dev/mapper/pve-root ro quiet, and yes i am sure because i have done pcie passthrough before on this specific server

 

[Neobin]

I got BOOT_IMAGE=/boot/vmlinuz-5.15.107-2-pve root=/dev/mapper/pve-root ro quiet

As you can see, there is no: intel_iommu=on present.
See here: [1], how to determine which bootloader is used and then edit the corresponding file and update the bootloader: [2].

[1] https://pve.proxmox.com/wiki/Host_Bootloader#sysboot_determine_bootloader_used
[2] https://pve.proxmox.com/wiki/Host_Bootloader#sysboot_edit_kernel_cmdline

 

[Aerialflame7125]

As you can see, there is no: intel_iommu=on present.
See here: [1], how to determine which bootloader is used and then edit the corresponding file and update the bootloader: [2].

[1] https://pve.proxmox.com/wiki/Host_Bootloader#sysboot_determine_bootloader_used
[2] https://pve.proxmox.com/wiki/Host_Bootloader#sysboot_edit_kernel_cmdline

Wait a minute.. i use Grub, not system-d, "cat /proc/cmdline" would that still display grub.cfg file changes?

 

[leesteken]

Wait a minute.. i use Grub, not system-d, "cat /proc/cmdline" would that still display grub.cfg file changes?

Yes, /proc/cmdline always displays the parameters of the running kernel, regardless of the bootloader.