BootableUsbStick

Creating a Bootable USB Stick

Requirements for this are

a Linux kernel - take it from your Debian installation,
a compatible set of modules packed into an initrd image (see Creating the Initial RAM Disk),
the Debian image you want to load into RAM (see Creating the Debian Image),
syslinux installed on your normal Debian system, "apt-get install syslinux" if not already done,
and (of course) the USB stick.

I expect bootable USB stick to be common today even if I had some difficulties with mine. USB boot support by your PC is can also be a source of problems.

Using a vfat USB stick

I think this is the most common scenario since all USB sticks come with vfat out of the box. But before going to the how-to, let's look at possible roadblocks:

One USB stick (which I know was bootable before) refused to be a boot medium at all.
Another was unable to host syslinux as boot loader but reformatting the drive with ext2 and applying extlinux to it worked.
A third (fresh out of the box) displayed the syslinux boot prompt but syslinux stopped working while loading files first. This was due to bad filenames.
One final problem might be the absence of required NLS modules. The default initrd image support codepage 497 and iso8859-1.

Here is how to proceed.

Plug the USB stick into a USB port, make sure that you know the device name (run "tail -f /var/log/messages" or appropriate while plugging).
Do not mount the device yet.
Assuming that the device name /dev/sdx and /dev/sdx1 (x is usually a, b, etc.) is the FAT partition, install the syslinux bootloader by running the command
```
# sylinux /dev/sdx1
```
Then mount the device
```
# mount /dev/sdx1 disk
```
and copy the kernel, the initrd and the linux image to it:
```
# cp vmlinuz-2.6.18-4-686 disk/vmlinuz
# cp initrd.img-2.6.18-4-686 disk/initrd.cgz
# linux.tgz disk/linux.tgz
```
Use only 8.3-style filenames. Although the filesystem is vfat, it's syslinux that requires short filenames.

Create the file syslinux.cfg in the USB stick's root directory. It should look like

default latest

timeout 100
prompt 1

label linux
  kernel vmlinuz
  append initrd=initrd.cgz im=linux.tgz

label test
  kernel vmlinuz
  append initrd=initrd.cgz im=test-linux.cgz

label latest
  kernel vmlinuz
  append initrd=initrd.cgz im=latest.cgz

Ignore that the configuration names image files which do not exist yet.

Ready, unmount the stick and try to boot from it.

Creating a Bootable USB Stick

Using a vfat USB stick

See also