diff --git a/doc/config_options.txt b/doc/config_options.txt
index d33b8cf97da..0c6e057541f 100644
--- a/doc/config_options.txt
+++ b/doc/config_options.txt
@@ -48,11 +48,21 @@ User keys can be used in search.
 ```
 
 ```{config:option} io.bus devices-disk
-:default: "`virtio-scsi`"
+:default: "`virtio-scsi` for block, `auto` for file system"
 :required: "no"
-:shortdesc: "Only for VMs: Override the bus for the device (`nvme`, `virtio-blk`, or `virtio-scsi`)"
+:shortdesc: "Only for VMs: Override the bus for the device"
 :type: "string"
+This controls what bus a disk device should be attached to.
 
+For block devices (disks), this is one of:
+- `nvme`
+- `virtio-blk`
+- `virtio-scsi` (default)
+
+For file systems (shared directories or custom volumes), this is one of:
+- `9p`
+- `auto` (default) (`virtiofs` + `9p`, just `9p` if `virtiofsd` is missing)
+- `virtiofs`
 ```
 
 ```{config:option} io.cache devices-disk
diff --git a/internal/server/metadata/configuration.json b/internal/server/metadata/configuration.json
index febfbc006b5..d28542f7899 100644
--- a/internal/server/metadata/configuration.json
+++ b/internal/server/metadata/configuration.json
@@ -60,10 +60,10 @@
 					},
 					{
 						"io.bus": {
-							"default": "`virtio-scsi`",
-							"longdesc": "",
+							"default": "`virtio-scsi` for block, `auto` for file system",
+							"longdesc": "This controls what bus a disk device should be attached to.\n\nFor block devices (disks), this is one of:\n- `nvme`\n- `virtio-blk`\n- `virtio-scsi` (default)\n\nFor file systems (shared directories or custom volumes), this is one of:\n- `9p`\n- `auto` (default) (`virtiofs` + `9p`, just `9p` if `virtiofsd` is missing)\n- `virtiofs`",
 							"required": "no",
-							"shortdesc": "Only for VMs: Override the bus for the device (`nvme`, `virtio-blk`, or `virtio-scsi`)",
+							"shortdesc": "Only for VMs: Override the bus for the device",
 							"type": "string"
 						}
 					},