[SOLVED] https://pve.proxmox.com/wiki/Pci_passthrough PT Mode

[jjg60]

https://pve.proxmox.com/wiki/Pci_passthrough says "Both Intel and AMD chips can use the additional parameter "iommu=pt", added in the same way as above to the kernel cmdline"

does this mean /etc/default/grub
entry for GRUB_CMDLINE_LINUX_DEFAULT becomes
GRUB_CMDLINE_LINUX_DEFAULT="quiet amd_iommu=on iommu=pt"
for the ADM CPU?

 

[janssensm]

Correct.
You wil get a confirmation in your journal like this
pve kernel: iommu: Default domain type: Passthrough (set via kernel command line)

 

[leesteken]

Yes, your change is correct but I expect it to not really do anything:

• You don't need amd_iommu=on because it is always on by default for AMD.
• iommu=pt sets the default mapping to identity for non-passed through devices and is not needed for PCI passthrough. It might improve the performance of devices that are not passed through but I have never read about any actual gains.

 

[jjg60]

thank you