Hi all,
for some reaseon, my message wasn't published. Second try, this time without the giant attachment.
I have an Intel server (SR2600URBRPR) in front of me. The disks in my server are connected via PCI card (Adaptec RAID 3405).
Now I would like to passthrough a PCI-E graphics card to a KVM guest. As this requires Intel VT-d, I configured the following options in the BIOS:
Intel VT for Directed I/O [Enabled] Interrupt Remapping [Enabled] Coherency Support [Disabled] ATS Support [Enabled] Pass-through DMA Support [Enabled]
Everything works so far, but when I add intel_iommu=on to the kernel line of my grub.conf, Dracut gives my a kernel panic while booting. I added "rdshell" to the command line and extracted the boot messages via dmesg (http://nilscaspar.ch/centos-dmesg.log). I think the main problem is this:
dracut Warning: No root device "block:/dev/disk/by-uuid/280234d1-dff5-4e04-b1ef-93d54cdcd825" found
But I doesn't make sense to me... As soon as I remove intel_iommu=on, everything works again (except the passthrough :P).
Regards, Nils
On 01/29/2013 01:16 PM, Nils Caspar wrote:
Everything works so far, but when I add intel_iommu=on to the kernel line of my grub.conf, Dracut gives my a kernel panic while booting. I added "rdshell" to the command line and extracted the boot messages via dmesg (http://nilscaspar.ch/centos-dmesg.log).
Similar behavior has been diagnosed as a hardware bug: https://bugzilla.redhat.com/show_bug.cgi?id=605888
Boot the system with the IOMMU off and find out what PCI device is at 05:01.0 using lspci. Assuming that it's not critical, try disabling or removing that component.
Thank you for your hint.
Boot the system with the IOMMU off and find out what PCI device is at 05:01.0 using lspci. Assuming that it's not critical, try disabling or removing that component.
I can not see a 05:01.0 using lspci. There is however 05:0e.0, which is the RAID controller (Adaptec RAID 3405). It's kind of a critical component, so I can not disable it. ;) Does this mean, it's impossible to make IOMMU work on this machine?
On 01/29/2013 11:35 PM, Nils Caspar wrote:
I can not see a 05:01.0 using lspci. There is however 05:0e.0, which is the RAID controller (Adaptec RAID 3405). It's kind of a critical component, so I can not disable it. ;) Does this mean, it's impossible to make IOMMU work on this machine?
Try booting the system without intel_iommu=on, but with the IOMMU enabled in the bios. Something has to be at 05:01.0. Do you see any Ricoh devices anywhere in lspci output?
Try booting the system without intel_iommu=on, but with the IOMMU enabled in the bios. Something has to be at 05:01.0. Do you see any Ricoh devices anywhere in lspci output?
That's exactly what I did.
I uploaded the full output of `lspci -vv`: http://nilscaspar.ch/centos-lspci.txt
Cheers, Nils
I did some experimenting with and without the RAID card installed. There are no DMAR errors, when the RAID card isn't present... Too bad! Anyone a suggestion for a RAID card that works with IOMMU?
Nils
I did some experimenting with and without the RAID card installed. There are no DMAR errors, when the RAID card isn't present... Too bad!
Just got this confirmed by Adaptec Support:
VT-D is not supported with our Adaptec RAID Controllers. You will need to disable this in the BIOS of the mainboard in order for the system to run in a stable way. This applies mainly to VMWARE but also to other linux configuration as you have seen.
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Gordon Messmer -
Nils Caspar