I said I'd never blog

First, I wish you all a happy new year, and I thank you for reading me :)

But let's get to this topic. Supposing you want to install NetBSD 5.0 onto your newly acquired Netbook (which has no CD-ROM drive), here's how you can create a bootable USB key with the necessary installation content.

Getting started

My other system is a NetBSD amd64 workstation, whereas the Netbook is i386. Once you have downloaded NetBSD sources to /usr/src:

# cd /usr
# cvs -d:anoncvs@anoncvs3.de.NetBSD.org:/cvsroot co -r netbsd-5 src

you are free to bootstrap a compilation environment, in /home/i386 for example:

# mkdir -p /home/i386/obj /home/i386/tools
# cd /usr/src
# ./build.sh -m i386 -O /home/i386/obj -T /home/i386/tools -u tools

Congratulations, you now have a cross-compiler for i386 on your system. What is usually a tedious task took only one command with the wrapper.

Compiling a kernel

It is easier to use NetBSD's build.sh wrapper again:

# cd /usr/src
# ./build.sh -m i386 -O /home/i386/obj -T /home/i386/tools -u kernel=INSTALL_FLOPPY

You should now have a kernel in /home/i386/obj/sys/arch/i386/compile/INSTALL_FLOPPY/netbsd. Let's make a copy in a more convenient location:

$ mkdir -p /tmp/netbook
$ cp /home/i386/obj/sys/arch/i386/compile/INSTALL_FLOPPY/netbsd /tmp/netbook/

This kernel is not yet usable as an installation kernel though: it is configured to run in RAM, but does not embed any such filesystem yet.

Creating a RAM disk

Again, this is quite straightforward:

# cd /usr/src/distrib/i386/ramdisks/ramdisk-big
# /home/i386/tools/bin/nbmake-i386

If all went well, you now have a ramdisk file in /home/i386/obj/distrib/i386/ramdisks/ramdisk-big/ramdisk-big.fs. If something went wrong, such as compiling restore (like for me), simply edit the list file and comment out this line as so:

#PROG	sbin/restore	sbin/rrestore

Let's make it more convenient again:

$ cp /home/i386/obj/distrib/i386/ramdisks/ramdisk-big/ramdisk-big.fs /tmp/netbook/

Preparing the kernel

We can now embed the ramdisk inside the kernel. It only takes this:

$ cd /tmp/netbook/
$ mdsetimage -v -s netbsd ramdisk-big.fs
$ gzip -9 netbsd && mv netbsd.gz netbsd-INSTALL.gz

This kernel is now able to start the installer. By booting it, we could already download and install a system, if the sets were available. Unfortunately, we may have to compile them ourselves at the moment.

Generating the sets

This should just work:

# cd /usr/src
# ./build.sh -m i386 -O /home/i386/obj -T /home/i386/tools -u sets

It will also help for the following step to copy the sets over:

$ cp -R /home/i386/obj/releasedir/i386/binary/sets /tmp/netbook/

We will also need a kernel, for which the GENERIC configuration should be safe:

# cd /usr/src
# ./build.sh -m i386 -O /home/i386/obj -T /home/i386/tools -u kernel=GENERIC

Creating the kernel set should be as simple as this:

$ cd /tmp/netbook/
$ cp /home/i386/obj/sys/arch/i386/compile/GENERIC/netbsd .
$ gzip -9 netbsd && mv netbsd.gz netbsd
$ tar -czvf kern-GENERIC.tgz ./netbsd

Make a bootable USB key

Now comes the tricky part. First, identify how your USB key is seen by the system. A good way to do so is to run:

$ tail -f /var/log/messages

and to read what the kernel has to say. It should print something like this:

/netbsd: sd0 at scsibus0 target 0 lun 0: <, , > disk removable
/netbsd: sd0: fabricating a geometry

which means, in my case, that the key is seen as sd0. If it is already formatted as a FAT volume, you should be able to mount it like this:

# mkdir -p /mnt/usb
# mount /dev/sd0e /mnt/usb

You can make sure that it is the case through the disklabel command:

# disklabel sd0
[...]
5 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
d:   2023424         0     unused      0     0        # (Cyl.      0 -    987)
e:   2021634        62      MSDOS                     # (Cyl.      0*-    987*)

(the d partition is virtual and represents the whole disk)

Starting with the obvious, it is time to copy the installation kernel and associated sets onto the USB key:

# cp /tmp/netbook/* /mnt/usb
# mv /mnt/usb/netbsd-INSTALL.gz /mnt/usb/netbsd

Booting will also require this file on the key:

# cp /usr/mdec/boot /mnt/usb

It is time to unmount the media:

# umount /mnt/usb

And finally, the following command will make the key bootable:

# installboot -v -o timeout=5 /dev/rsd0e /usr/mdec/bootxx_msdos

Troubleshooting

If the key does not boot, it can be that:

• there is already a bootloader in the Master Boot Record (MBR)
• the partition needs to be active
• the partition is incorrectly formatted

You may refer to the manual page of installboot(8) for more details. Alternatively, it is also possible to use grub to boot the key.