Subject: How to use a file system image for Linux DomU ?
To: None <port-xen@netbsd.org>
From: Thierry Herbelot <thierry@herbelot.com>
List: port-xen
Date: 07/25/2005 19:22:26
Hello,

I'm toying with Xen (Dom0 with NetBSD and Debian with 2.4 and 2.6 kernels)

I'm using a recent snapshot of -Current for NetBSD / Dom0 :
NetBSD 3.99.7 (XEN0) #0: Wed Jul  6 19:27:45 UTC 2005  
jmc@faith.netbsd.org:/home/builds/ab/HEAD/i386/200507060000Z-obj/home/builds/ab/HEAD/src/sys/arch/i386/compile/XEN0

with most recent xentools :
xentools20-2.0.6nb1 Userland Tools for Xen

I have been able to create "physical" partitions to use with NetBSD/DomU (wd0g 
to wd0j for 4 NetBSD DomUs and /dev/hdb7 to /dev/hdb11 for Linux DomUs)

The Linux DomUs are shared between the NetBSD and Linux Dom0s.

These Linux and NetBSD DomUs, hosted in "physical" partitions work as 
expected, either under NetBSD/Dom0 or Linux/Dom0
I also have a NetBSD/DomU hosted in a linux-based file under Linux/Dom0 (with 
another file-hosted NetBSD/DomU under NetBSD/Dom0)

-------------------------------------

What I can not seem to be able to do is to start a Linux DomU from a file 
image in a NetBSD partition : with a xen config file containing :
disk=['phy:/dev/vnd0d,0x801,w','phy:/dev/wd1j,0x802,w']
when previoulsy :
vnconfig vnd0 debian-root
debian-root is a 400MB file formatted as ext2fs from NetBSD

(The error messages are detailed below)

has someone been able to run an image-based Linux DomU under NetBSD/Dom0 ?

	Cheers

	TfH

(as this was crucial for partition-based Linux/DomUs, the /dev/vnd0d has been 
formatted from NetBSD using e2fsprogs-1.32)

-------------------------------------

When I start the image-based Linux DomU and a vmlinuz-2.4.30-XenU kernel :
xm create -c dom5.debian.image
Using config file "dom5.debian.image".
Started domain Debian-dom5, console on port 9614
************ REMOTE CONSOLE: CTRL-] TO QUIT ********
Linux version 2.4.30-xenU (xenod@freefall.cl.cam.ac.uk) (gcc version 3.3.3 
20040412 (Red Hat Linux 3.3.3-7)) #1 Sun May 22 11:52:30 BST 2005
....
ip_conntrack version 2.1 (256 buckets, 2048 max) - 288 bytes per conntrack
ip_tables: (C) 2000-2002 Netfilter core team
NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
802.1Q VLAN Support v1.8 Ben Greear <greearb@candelatech.com>
All bugs added by David S. Miller <davem@redhat.com>
VFS: Mounted root (ext2 filesystem) readonly.
Freeing unused kernel memory: 60k freed

There, the Linux DomU seems "stuck" : there is no progress and no new message 
in the console.

the "non-running" domain seems to be spinning and sucking all CPU cycles :
xm list ; sleep 10 ; xm list
Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Debian-dom5       14       32    0  -----    609.3    9614
Domain-0           0       63    0  r----   2959.8
Name              Id  Mem(MB)  CPU  State  Time(s)  Console
Debian-dom5       14       32    0  -----    622.2    9614
Domain-0           0       63    0  r----   2962.5

-------------------------------------

When I start the image-based Linux DomU and a vmlinuz-2.6.11.10-xenU :
Linux version 2.6.11.10-xenU (xenod@freefall.cl.cam.ac.uk) (gcc version 3.3.3 
20040412 (Red Hat Linux 3.3.3-7)) #1 Sun May 22 11:42:16 BST 2005
BIOS-provided physical RAM map:
 Xen: 0000000000000000 - 0000000002000000 (usable)
32MB LOWMEM available.
....
NET: Registered protocol family 1
NET: Registered protocol family 17
VFS: Mounted root (ext2 filesystem) readonly.
Freeing unused kernel memory: 112k freed
attempt to access beyond end of device
sda1: rw=0, want=2576980378, limit=819200
Buffer I/O error on device sda1, logical block 3435973836
[multiply repeated identical error message]