Create a Bootable Device

This page is about creating directly customizable boot devices. The creation (flashing) of a read-only (iso9660 CD filesystem) image onto installation media is covered by the Installation page.

A directly customizable Alpine Linux boot medium is basically an Alpine system in diskless or data disk-mode installed to (booting from) a device with a writable filesystem.

The customization of the local configuration (.apkovl) and the package cache may also be stored on the same device, as long as the device is not write-locked.

Requirements

In order to follow this document, you will need:

• An Alpine Linux CD-ROM or an .iso file containing the desired Alpine release (Download).
• A device like an USB drive (flash, external HD, card reader, etc.) or a CF "CompactFlash", or SDcard.

Using setup-bootable

The preferable method to create a custom bootable device now is to follow the Installation for a diskless or data mode system on the device, and use the setup-bootable script to make the device bootable.

Manually copying Alpine files

This process applies to Alpine Linux 1.9.0 or later.

It describes how to manually create a custom (writable) USB boot device.

Copy ISO content to USB stick as individual files

Warning: We assume here sda is your USB stick which would hold bootable Alpine Linux files.

The following procedure is for Alpine Linux distribution itself, if you are using other Linux distro or other operating system you should know the best how to install syslinux and where mbr.bin file is located on your filesystem.

1. If you created a new partition above, format the flash medium with a FAT32 filesystem (replacing sda with your flash medium name):

   apk add dosfstools
   mkdosfs -F32 /dev/sda1

2. Install syslinux and MBR (replacing sda with your flash medium name):

   apk add syslinux
   dd if=/usr/share/syslinux/mbr.bin of=/dev/sda
   syslinux /dev/sda1

3. Copy the files to the flash medium (replacing sda with your flash medium name):

   mkdir -p /media/sda1 mount -t vfat /dev/sda1 /media/sda1 cd /media/cdrom cp -a .alpine-release * /media/sda1/ umount /media/sda1

4. (Optional) Remove any apkovl files that were transfered as part of the copy process. This should be done if you wish to have a fresh install. Replace sda with your flash medium name)

   mount -t vfat /dev/sda1 /media/sda1 rm /media/sda1/*.apkovl.tar.gz umount /media/sda1

Troubleshooting

Wrong Device Name

If you cannot boot from the flash medium and you see something like:

Mounting boot media failed.
initramfs emergency recovery shell launched. Type 'exit' to continue boot

then it is likely that the device name in syslinux.cfg is wrong. You should replace the device name in this line:

append initrd=/boot/grsec.gz alpine_dev=usbdisk:vfat modules=loop,cramfs,sd-mod,usb-storage quiet

with the proper device name.

• For boot from USB, the device name should be 'usbdisk' (as shown above)
• For other options, you can run cat /proc/partitions to see the available disks (i.e. 'sda' or 'sdb')

Non-FAT32 Filesystems

When your flash medium is formatted with a filesystem other than FAT32, you might have to specify the necessary filesystem modules in the boot parameters.

To do so, mount the flash medium and change the syslinux.cfg file line from

append initrd=/boot/grsec.gz alpine_dev=usbdisk:vfat modules=loop,cramfs,sd-mod,usb-storage quiet

to

append initrd=/boot/grsec.gz alpine_dev=usbdisk:ext3 modules=loop,cramfs,sd-mod,usb-storage,ext3 quiet

in the case of an ext3 formatted partition. A similar procedure might apply to other filesystems (if they are supported by syslinux and the Alpine Linux kernel).

Finishing installation

After one has booted the previously created Alpine Linux bootable USB medium, one has to prepare USB stick to hold local customizations and run setup-alpine to finish the installation.

First let's find out where is our just booted USB media mounted, the location could vary.

# mount | grep /media
/dev/sda1 on /media/sda1 type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=utf8,shortname=mixed,errors=remount-ro)

Create local directory on USB media to hold local APK cache (see APK Local Cache for details).

# mount -o remount,rw /media/sda1
# mkdir /media/sda1/cache
# setup-apkcache /media/sda1/cache
# ls -l /etc/apk/cache
lrwxrwxrwx    1 root     root            17 Oct 19 13:16 /etc/apk/cache -> /media/sda1/cache

Now run setup-alpine and proceed until a question about local disk selection - in diskless mode we won't use any disk (ie. our bootable media files is basically untouched) and we are going to use sda1 to hold our system customization.

# setup-alpine
...
Which disk(s) would you like to use? (or '?' for help or 'none') [none] 
Enter where to store configs ('floppy', 'sda1', 'usb' or 'none') [sda1]: 
Enter apk cache directory (or '?' or 'none') [/media/sda1/cache]:

After the installer finished you can see how many created/modified files are detected and will be added to the backup:

# lbu status
# lbu status | wc -l
59
# lbu commit
# ls -l /media/sda1/*apkovl.tar.gz
-rwxr-xr-x    1 root     root          9591 Oct 19 15:23 /media/sda1/foo.apkovl.tar.gz

Now all the customization are saved into the foo.apkovl.tar.gz compressed tarball on the USB stick itself.

Troubleshooting

Slow USB Devices

Specifying the 'waitusb=X' option at the end of the syslinux.cfg line might help with certain USB devices that take a bit longer to register. X stands for the amount of seconds kernel will wait before looking for the installation media.

append initrd=/boot/grsec.gz alpine_dev=usbdisk:vfat modules=loop,cramfs,sd-mod,usb-storage quiet waitusb=3

CF card readers

Some CF card readers have problems with the faster CF cards on the market. If you experience problems booting the CF card even after checking BIOS settings, you may need to use an older card.

Also, many CF card readers don't support DMA correctly, so you may need to add nodma to the append line of the syslinux.cfg file.