Temporary fix for disk device checks

The check for disk devices was completly broken, fix it temporarily.

This check is also kinda wrong, but is still an improvement over the
current test, so submit it waiting for a better idea.

TODO

@@ -28,6 +28,19 @@ Bugs to fix and features to add for 5.0
    are examples, and shouldn't cover every single scenario. They
    are also easy to write.
 
+* Think again about disk_device checks :
+
+   Newer Xen provides "xvda", older provided "sda". The current check for
+   valid values of disk_device (used for root device in domU /etc/fstab)
+   does only allow those values.
+   This forbids any deployment of LVM/RAID _inside_ domU, which cannot
+   be created by xen-tools anyway. So the current check is fine with the
+   current possibilities of xen-tools, but could become a limitation.
+   - Is it possible/wanted to "query" xend for default device names ?
+   - Is it possible to create /dev/mapper devices with xend conf ?
+   - Can we just avoid to ask for this value and not specify the device
+   in /etc/fstab (and use /dev/root, /dev/by-uuid, or anything ?)
+
 * xen-create-image --dist=... / sources.list generation should be more fine-grained
 
    xen-tools should offer the possibility to enable/disable

bin/xen-create-image

@@ -1553,8 +1553,8 @@ sub checkOption
             message => "must be a serial device (tty*, hvc* or xvc*).\n",
         },
         diskDev => {
-            check   => qr/^(?:\/dev\/)?(?:tty|hvc)[0-9]+$/,
-            message => "must be a disk device (tty*, hvc*).\n",
+            check   => qr/^(?:\/dev\/)?(?:xvd|sd)[a-z][0-9]+$/,
+            message => "must be a disk device (xvd*, sd*).\n",
         },
         ipv4 => {
             check   => qr/^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/,

etc/xen-tools.conf

@@ -298,7 +298,7 @@ btrfs_options    = defaults
 #
 #  If you're using the lenny or later version of the Xen guest kernel you will
 # need to make sure that you use 'hvc0' for the guest serial device,
-# and 'xvdX' instead of 'sdX' for serial devices.
+# and 'xvdX' instead of 'sdX' for disk devices.
 #
 #  You may specify the things to use here:
 #