i915 pass-through: 'pipe error 0x00000880' ?

C

celemine1gig

Active Member
May 22, 2020
77
16
28
55
Hi guys,

I have a Intel CoffeeLake system (i3-8300 on C246 chipset), with installed Proxmox VE 6.2 (latest update status) that I wanted to use with several containers and one VM with fully passed-through i915 graphics.
Found a setup, that is nearly fully working (vm conf excerpt):
Code: 
...
hostpci0: 00:1f,pcie=1
hostpci1: 00:02,pcie=1,x-vga=1
machine: pc-q35-4.1   (<== if I set anything newer than '4.1', the display output will no longer work)
serial0: socket
vga: serial0
...

Now, that setup is already working pretty well, besides the following issue:
I have a Debian testing VM setup, that gets its syslog flooded to no end with "pipe error 0x00000880" error messages from i915.

I did some google searching and found the following bug report with a very similar, but not exactly the same error message:
https://bugs.freedesktop.org/show_bug.cgi?id=109099

Went ahead with the described workaround and rebuilt the Debian VM's kernel, with the mentioned code change in the "i915_drv.h" file, forcing the "intel_vtd_active" function to return "true".
With that, the errors are gone and it seems to work just fine.

Which is great, however, I was wondering:
- Is someone else is also experiencing this?
- Is it a already known issue?
- Why do I have to force the vt-d detection?

Thanks in advance for your comments.

Best regards,
Ingmar
 
And last update:
The patch from kernel org worked flawlessly on the 5.9.1 kernel of my debian testing VM.
 
I have an AsRock C246 with Coffee Lake as well, but I'm unable to even see any IOMMU groups in proxmox. Can you share what you have in grub and modules to get this working? I've tried seemingly every combination in the documentation.
 
Last edited:
Tim, are you sure, that grub is even used?
Have a look at "/etc/kernel/cmdline", edit as required and then run "pve-efiboot-tool refresh". Besides, follow the usual how-tos.
 
You must log in or register to reply here.
Top Bottom