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Revision as of 22:19, 12 September 2010 by Nik (talk | contribs) (add note about netbsd networking in Xen4)

c33ris2's gentle guide to installing NetBSD in a prgmr DomU (January 2009)

Note: By June 2010 (or earlier) some of the dom0 hosts have packed the installer files into the /distros collection available to many recovery images. In these cases, the fetching activity is no longer required.

Note for mantle/chessboard users: Mantle is currently running Xen 4.0.1. There is a bug in NetBSD that breaks networking when running in a Xen4 domU.

Getting Started

Installing NetBSD as DomU is easy, but not trivial.

Boot your preconfigured system, in order to discover, and note for later use, YOUR_IP, NETMASK, GATEWAY, and NAMESERVER as follows:

Run 'ifconfig eth0' and note your "inet addr" and "Mask" values.
Run 'route' or 'ip route' and note the IP of the default gateway.
Run 'cat /etc/resolv.conf' and note the IP of the nameserver

From the control menu on your dom0 host, destroy/shutdown the instance, and restart ("create/start") it, selecting the "rescue" option from the bootloader. Login as 'root'.

Your fixed disk, as known to the linux rescue image, is /dev/xvda. Later, when booted to the NetBSD installer, it is identified as /dev/xbd0.

For NetBSD, this disk must be partitioned, and the NetBSD installer files placed therein.

fdisk /dev/xvda

From within fdisk,

  • delete the existing partition, *which will destroy your current OS image and data*
  • create a new primary partition #1, with first cylinder at default=1 and last cylinder at +32M
  • write the new parition table to the disk.
  • exit fdisk

Success to this point is evidenced by the prseence of /dev/xvda1 which must now be formatted, mounted, and a /boot directory created:

mkfs.ext2 /dev/xvda1
mount -n /dev/xvda1 /mnt
mkdir /mnt/boot

If the file 'netbsd64.tar.gz' exists in /distros, skip over to #Unpacking the Installer

Otherwise you'll have to proceed here with

Fetching the Installer

Substituting actual values observed (above) for YOUR_IP, NETMASK, GATEWAY, and NAMESERVER ...

ifconfig eth0 up YOUR_IP/NETMASK
route add default gw GATEWAY eth0
echo "nameserver NAMESERVER" >/etc/resolv.conf

wget and extract to /mnt/boot/ :

(or newer)

Create a file boot/grub/menu.lst with this content:

timeout 5

title NetBSD run
        root (hd0,0)
        kernel /boot/netbsd-XEN3_DOMU

title NetBSD install
        root (hd0,0)
        kernel /boot/netbsd-INSTALL_XEN3_DOMU

Skip to #Booting the Installer

Unpacking the Installer

This section presumes the presence, in the rescue instance, of /distros/netbsd64.tar.gz
Unpack this into the new boot menu, and shutdown.

tar zxf /distros/netbsd64.tar.gz -C /mnt/boot/
shutdown -h now

Booting the Installer

Returning to the control menu on your dom0 host, destroy/shutdown your instance if it is running, and create/start it again, this time selecting first the "user bootloader configuration" from the options presented by the dom0, and after that select the installer from your new user bootloader. This should take you to the NetBSD Installer, for which a tutorial exists at

Install onto xbd0

When presented with the option, choose
b: Use existing partition sizes
The next screen should show the existing BSD-disklabel partitions, as follows for a 6G allocation.

    Start  MB   End  MB  Size  MB FS type    Newfs Mount Mount point
    --------- --------- --------- ---------- ----- ----- -----------
 a:         0         0         0 unused
 b:         0         0         0 unused
 c:         0      6143      6144 NetBSD partition
 d:         0      6143      6144 Whole disk
 e:         0        38        39 Linux Ext2
 f:         0         0         0 unused

If you're new to NetBSD partitioning, which I am, which is why I'm writing this, refer to this NetBSD Guide section

The purpose of examining this screen is to note that the Linux Ext2 partition used for the installer occupies the first 39 (numbered 0 thru 38) sectors of the partition. We need to set the NetBSD root after that, starting with sector 39.

Select "x: Partition sizes ok" and "no" to the opportunity to edit the partition table again. The installation will be aborted and you'll be returned to an earlier screen, which is intended by this tutorial. Proceed as before through the next few screens, but this time select
a: Set sizes of NetBSD partitions
which will set up the default root and swap partitions.

Optional, Recommended: (but I haven't been able to do this successfully yet) "Add a user defined partition" at /boot so that you can update the kernels and adjust the menu.lst later. The size should be as noted earlier for the linux partition, 39MB in this example.

Select "accept these sizes", and you'll get a screen with one more chance, which we'll take, to modify the partitions, by selecting the DiskLabel 'a' and changing the start point from 0 to 39 (MB).

If you added a label for /boot, you'll see it in the table, and it needs to be modified. Set the start to 0, and in response to the size prompt, answer with 'a' to have the partition end at the beginning of disklabel 'a'.

Here is an example disklabel setup for a 3072M disk with a 32M boot partition:

     Start  MB   End  MB  Size  MB FS type    Newfs Mount Mount point
    --------- --------- --------- ---------- ----- ----- -----------
 a:        31      2912      2882 FFSv1      Yes   Yes   /
 b:      2913      3040       128 swap
 c:         0      3071      3072 NetBSD partition
 d:         0      3071      3072 Whole disk
 e:         0        30        31 Linux Ext2
 f:         0         0         0 unused
 g: Show all unused partitions
 h: Change input units (sectors/cylinders/MB)
>x: Partition sizes ok

Continue with the installation.

Install by FTP

Use the actual values observed (above) for
when prompted by the installer

The installation of NetBSD-5.0.2 is now complete.  The system should boot
from hard disk.  Follow the instructions in the INSTALL document about final
configuration of your system.  The afterboot(8) manpage is another
recommended reading; it contains a list of things to be checked after the
first complete boot.

At a minimum, you should edit /etc/rc.conf to match your needs.  See
/etc/defaults/rc.conf for the default values.


Something's wrong :( with the way I disklabelled /boot. Everything is fine if I skip that step.