[PATCH pve-docs 13/13] qm: Document efi-firmware VM option

[Christian Ludwig <christian_ludwig@genua.de>]

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Signed-off-by: Christian Ludwig <christian_ludwig@genua.de>
---
 qm.adoc | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/qm.adoc b/qm.adoc
index 5b46cdc..141187b 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -1246,6 +1246,39 @@ NOTE: The markers `ms-cert=2023` and `ms-cert=2023w` may indicate partial
 enrollment. The VM start task log will warn about this. You should apply the
 enrollment procedure for such EFI disks too.
 
+[[qm_custom_efi_firmware]]
+Custom EFI Firmware
+^^^^^^^^^^^^^^^^^^^
+
+By default, {pve} uses the system-provided OVMF firmware images. If you need a
+custom or vendor-specific EFI firmware code image, you can override the default
+firmware with the `efi-firmware` VM option.
+
+The firmware image must first be uploaded to a storage that has the
+`efi-firmware` content type enabled.
+
+To configure a VM to use a custom firmware image:
+
+----
+# qm set <vmid> -efi-firmware <storage>:efi-firmware/<name>
+----
+
+For example:
+
+----
+# qm set 100 -efi-firmware local:efi-firmware/custom-ovmf-code.fd
+----
+
+NOTE: The `efi-firmware` option requires `bios` to be set to `ovmf`. The
+custom image replaces only the firmware code (pflash0); the EFI vars disk
+(`efidisk0`) is still used as normal for storing UEFI variables.
+
+To remove a custom firmware assignment and revert to the default OVMF image:
+
+----
+# qm set <vmid> -delete efi-firmware
+----
+
 [[qm_tpm]]
 Trusted Platform Module (TPM)
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- 
2.34.1