pci-passthrough: expand IOMMU section with notice about BIOS

note that one must enable IOMMU support in the BIOS/UEFI.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

diff --git a/qm-pci-passthrough.adoc b/qm-pci-passthrough.adoc
index dfc3d6ea777b41fe9a70b536230bd2374bdbdb36..edaa01f5011945fdf8eb20d03a2469b6df2d9cf0 100644 (file)
--- a/qm-pci-passthrough.adoc
+++ b/qm-pci-passthrough.adoc
@@ -45,7 +45,11 @@ some configuration to enable PCI(e) passthrough.
 
 .IOMMU
 
-The IOMMU has to be activated on the
+First, the IOMMU support has to be enabled in your BIOS/UEFI. Most often, that
+options is named `IOMMU` or `VT-d`, but check the manual for your motherboard
+for the exact option you need to enable.
+
+Then, the IOMMU has to be activated on the
 xref:sysboot_edit_kernel_cmdline[kernel commandline].
 
 The command line parameters are: