Create a Bootable Device

This page is about creating customizable boot devices for diskless or data disk-mode Alpine Linux using a writable filesystem i.e. not iso9660, so that local customizations like apkovl files and cached packages can be stored. It allows to also upgrade the kernel with its modules and firmware that is used to boot the system with the update-kernel script.
 
== Requirements ==
* An Alpine Linux Installation Media, can be CD/DVD/USB. 
* A customizable boot device that can be a USB-Stick/CompactFlash/SDCard etc., or harddisk partition for the diskless or data mode Alpine linux.
== Using setup-bootable ==
setup-bootable script is the preferred method to create a directly customizable bootable device on a FAT32 filesystem. For other filesystems refer Manually copying Alpine files. 
# Complete the Installation until the base configuration step by booting from an Alpine Linux Installation Media. Perform the initial execution of <Code>setup-alpine</Code> as described in the base configuration step answering "none" to all disk-related questions. Ensure that customizable boot device is already plugged in or installed. Install the necessary tools to prepare the customizable bootable device so that it doesn't have weird stuff that affects later:
#: 
# Run <Code>lsblk</Code> to figure out what the disk to turn into your bootable device. Let's say it's /dev/sda for this example, change as needed:
#: 
#: 
# Create a partition sda1 with the desired size, set the type to win95 fat, and set the bootable flag on it. Format the newly created partition. Alter the device name i.e as needed. 
#: 
# Figure out where your install media files are mounted. if you run a command, you should see a read only mount for something like /media/cdrom or /media/usb or something else, depending on your environment. Let's use /media/cdrom for the install media files and /dev/sda1 for the customizable boot device:
#: 
# After that's done, remove Installation Media and reboot the system. 
# Once the system boots from the customizable boot device , login as root and run setup-alpine</Code> once again to complete the Installation until the base configuration step. 
#: # 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]:
# For the question on disk to use, select none. 
# The script asks about storing configs. Choose the customizable boot device.('sda1' in this example). 
# Then the script asks you for apk cache directory. Accept the default or type as follows i.e . Refer APK Local Cache for more details.
# Always remember to run <Code>lbu ci</Code> to commit the above changes to disk.
#: 
# Test/verify by rebooting and seeing that your alpine setup is preserved in the customizable boot device.
== Manually copying Alpine files ==
If you do not want to use <Code>Setup-bootable</Code> script or need non-FAT32 partitions, you can manually create a customizable boot device by manually copying Alpine Linux Files and install the bootloader to make the device bootable.
=== Copying ISO/tarball contents to a USB stick ===
This method is written for copying files from an Alpine ISO file but also works for Alpine tarballs (.tar.gz files) with a one line tweak (see below).
# Install some prerequisites. (If you're not currently using Alpine Linux then you probably have these installed already, otherwise you'll have to figure out how to install them.)
#: 
# Set the environment variable 'mydev' to the device file name of the USB stick that Alpine Linux is to be installed to:
#: 
#: 
#: 
# Make sure that the target drive's existing partitions, if any, are not mounted:
#: 
# Copy and paste the following as a single command to wipe the target drive, create an MBR partition table, and create a single FAT32 partition (you can ignore any "Partition #1 contains a vfat signature." warning message):
#: 
# Format the new FAT32 partition with a FAT32 filesystem:
#: 
# Copy the syslinux executable boot code into the bootstrap code area of the MBR boot sector (if you're not currently using Alpine Linux you may need to adjust the path to syslinux's mbr.bin file):
#: 
# Install the syslinux bootloader files onto the FAT32 filesystem. (Ignore the "Hidden (2048) does not match sectors (62)" messages - modern systems use the partition table. If you are getting "no previous syslinux boot sector found" error, try adding --install flag):
#: 
# Copy the Alpine files to the FAT32 filesystem (to copy the contents of an Alpine tarball instead, see next item):
#: 
# If you instead want to copy the contents of an Alpine tarball, do this:
#: 
# (Optional) Remove any .apkovl overlay files that were transferred as part of the copy process. Do this if you want an unmodified, vanilla install.
#: 
=== 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/sdU1 on /media/sdU1 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/sdU1
 # mkdir /media/sdU1/cache
 # setup-apkcache /media/sdU1/cache
 # ls -l /etc/apk/cache
 lrwxrwxrwx 1 root root 17 Oct 19 13:16 /etc/apk/cache -> /media/sdU1/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 sdU1 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', 'sdU1', 'usb' or 'none') [sdU1]: 
 Enter apk cache directory (or '?' or 'none') [/media/sdU1/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/sdU1/*apkovl.tar.gz
 -rwxr-xr-x 1 root root 9591 Oct 19 15:23 /media/sdU1/foo.apkovl.tar.gz
Now all the customization are saved into the foo.apkovl.tar.gz compressed tarball on the USB stick itself.
== Troubleshooting ==
=== Wrong Device Name ===
If you cannot boot from the boot device 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 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 the boot device is formatted with a filesystem other than those supported by default, the necessary initfs features need to be added to the modloop using update-kernel. See: Alpine_Linux_package_management#Upgrading_.22diskless.22_and_.22data.22_disk_mode_installs
Mount the boot device and edit the file.
Then locate the "append" line, and change the alpine_dev= setting to match the used filesystem and add the filesystem's kernel module to the modules= list.
For example, change
 append [...] alpine_dev=usbdisk:vfat modules=loop,cramfs,sd-mod,usb-storage quiet
to
 append [...] alpine_dev=usbdisk:ext4 modules=loop,cramfs,sd-mod,usb-storage,ext4 quiet
in the case of an ext4 formatted partition. (Or correspondingly for other filesystems, if they are supported by syslinux and the Alpine Linux kernel.)
=== 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.
== See Also ==
* APK Local Cache
* Alpine local backup
* update-kernel script 
Category:InstallationCategory:Diskless