>Number:         29856
>Category:       port-xen
>Synopsis:       Cannot add vnd files in domU when it's already running
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-xen-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Apr 01 10:02:00 +0000 2005
>Originator:     Juan RP
>Release:        NetBSD 3.99.2
>Organization:
>Environment:
System: NetBSD Mandylion 3.99.2 NetBSD 3.99.2 (GATEWAY_) #1: Thu Mar 31 18:41:13 CEST 2005 juan@Nocturno:/home/juan/build/obj/sys/arch/i386/compile/GATEWAY_ i386
Architecture: i386
Machine: i386
>Description:

	When there's a domU running, you might want to add
	another vbd device, but it doesn't work:

	dom0:

	$ xm create /etc/xen/foo 
	$ dd if=/dev/zero of=mydisk.img count=512 bs=1m
	$ vnconfig vnd0 mydisk.img
	$ xm vbd-create nbsd1 phy:/dev/vnd0a wd1d w

	domU:

XenU# disklabel xbd1d
disklabel: Can't read master boot record 0: Input/output error
# /dev/rxbd1d:
type: ESDI
disk: Xen Virtual ESDI
label: default label
flags:
bytes/sector: 512
sectors/track: 2048
tracks/cylinder: 1
l.      0 -    781*)
 d:   1600000         0     4.2BSD      0     0     0  # (Cyl.      0 -    781*)
disklabel: boot block size 0
disklabel: super block size 0
disklabel: partitions a and d overlap
XenU#

	You cannot disklabel or newfs it, when the vnd files
	are specified in the config file and they are started
	at boot time, it works.
	
>How-To-Repeat:

	See above.
>Fix:
	As a workaround, specify the vnd files when the domU
	is created (at boot time), that way works.