Remastering the Install ISO
Related articles
Remastering the official Arch Linux install ISO image is not necessary for most applications. However, it may be desirable in some cases.
- Basic hardware is not supported by the core install. (rare)
- Installation on a non-internet capable machine.
- Deployment of Arch Linux on many similar machines, requiring the same installation procedure.
As these ISOs are bootable, they can also be used for system rescue, testing, project demos, and more.
Contents
Archiso
It is often preferable to rebuild the installation ISO with Archiso, instead of remastering an existing ISO.
Manually
How it works
The installer ISO contains two separate archlinux systems. One for 32 bit (i686) and one for 64 bit (x86_64). The root filesystems of those systems are stored in arch/i686/airootfs.sfs
and arch/x86_64/airootfs.sfs
. The kernels and initramfs are in arch/boot/i686
and arch/boot/x86_64
. This means in order to fully remaster the ISO, you have to do your changes for both the 32 bit and the 64 bit system.
When booting, the initramfs will search for the device it was booted from via its label, ARCH_201410
for example, and will mount the root filesystem for the correct architecture.
Extracting the ISO
To remaster the Arch Linux ISO, you will need a copy of the original ISO image. Download it from the download page
Now, create a new directory to mount the ISO:
# mkdir /mnt/archiso
Mount the ISO to this directory (due to the nature of ISOs, the result is read-only):
# mount -t iso9660 -o loop /path/to/archISO /mnt/archiso
Copy the contents to another directory, where they can be edited:
$ cp -a /mnt/archiso ~/customiso
Customization
Modifying the x86_64 system
Change into the directory of the x86_64 system:
$ cd ~/customiso/arch/x86_64
Unsquash airootfs.sfs
(to squashfs-root
):
$ unsquashfs airootfs.sfs
Now you can modify the content of the system in squashfs-root
. You can also chroot into this system to install packages etc.:
# arch-chroot squashfs-root /bin/bash
To be able to install package, you have to initialise the pacman keyring:
(chroot) # pacman-key --init (chroot) # pacman-key --populate archlinux
If the kernel or initrd is updated, additional steps are required. In this case you have to install archiso inside the chroot and change the content of /etc/mkinitcpio.conf
:
(chroot) # pacman -Syu --force archiso linux (chroot) # nano /etc/mkinitcpio.conf
Change the line that says HOOKS="...
to:
HOOKS="base udev memdisk archiso_shutdown archiso archiso_loop_mnt archiso_pxe_common archiso_pxe_nbd archiso_pxe_http archiso_pxe_nfs archiso_kms block pcmcia filesystems keyboard"
Now update the initramfs:
(chroot) # mkinitcpio -p linux
When you are done, create a list of all installed packages, clean the pacman cache and exit the chroot:
(chroot) # LANG=C pacman -Sl | awk '/\[installed\]$/ {print $1 "/" $2 "-" $3}' > /pkglist.txt (chroot) # pacman -Scc (chroot) # exit
If you updated the kernel or the initramfs, copy them over to the system:
$ cp squashfs-root/boot/vmlinuz-linux ~/customiso/arch/boot/x86_64/vmlinuz $ cp squashfs-root/boot/initramfs-linux.img ~/customiso/arch/boot/x86_64/archiso.img
Move the list of packages:
$ mv squashfs-root/pkglist.txt ~/customiso/arch/pkglist.x86_64.txt
Now recreate airootfs.sfs
:
$ rm airootfs.sfs $ mksquashfs squashfs-root airootfs.sfs
Cleanup:
# rm -r squashfs-root
Now update the MD5 checksum of airootfs.sfs
:
$ md5sum airootfs.sfs > airootfs.md5
Modifying the i686 system
Follow the same steps as for the x86_64 system but with the following differences:
- In every command use
i686
instead ofx86_64
- When doing the chroot, use this command instead:
# setarch i686 arch-chroot squashfs-root /bin/bash
Modifying the EFI boot image
If you have updated the kernel or the initramfs and wish to boot on EFI systems, update the EFI boot image.
You will need dosfstools as the EFI boot image is a FAT16
filesystem.
$ mkdir mnt # mount -t fat -o loop ~/customiso/EFI/archiso/efiboot.img mnt $ cp ~/customiso/arch/boot/x86_64/vmlinuz mnt/EFI/archiso/vmlinuz.efi $ cp ~/customiso/arch/boot/x86_64/archiso.img mnt/EFI/archiso/archiso.img
If you see No space left on device
errors, you might need to resize efiboot.img
.
You can also create a new efiboot.img
and copy the old files (replace 50
with the required size).
$ dd if=/dev/zero bs=1M count=50 of=efiboot-new.img $ mkfs.fat -n "ARCHISO_EFI" efiboot-new.img $ mkdir new # mount -t fat -o loop efiboot-new.img new $ cp -r mnt/* new/ # umount new mnt $ mv efiboot-new.img ~/customiso/EFI/archiso/efiboot.img
And use the new efiboot.img
as above.
Create a new ISO
Create a new ISO image with genisoimage
, which is part of cdrkit.
$ genisoimage -l -r -J -V "ARCH_201209" -b isolinux/isolinux.bin -no-emul-boot -boot-load-size 4 -boot-info-table -c isolinux/boot.cat -o ../arch-custom.iso ./
The resulting ISO image will boot only from CD, DVD or BD. For booting from USB stick or hard disk, it needs the isohybrid feature. This can be achieved by postprocessing the ISO by program isohybrid included in syslinux. Officially, the version of installed SYSLINUX has to be the same as the version of /isolinux/isolinux.bin in the ISO. It is not known whether really incompatible version combinations exist.
An alternative to genisoimage plus isohybrid can be derived from the xorriso run of mkarchiso.
$ iso_label="ARCH_201209" $ xorriso -as mkisofs \ -iso-level 3 \ -full-iso9660-filenames \ -volid "${iso_label}" \ -eltorito-boot isolinux/isolinux.bin \ -eltorito-catalog isolinux/boot.cat \ -no-emul-boot -boot-load-size 4 -boot-info-table \ -isohybrid-mbr ~/customiso/isolinux/isohdpfx.bin \ -output arch-custom.iso \ ~/customiso
Option -isohybrid-mbr needs an MBR template file. Most probably there is already such a file /isolinux/isohdpfx.bin in the original ISO, which matches the SYSLINUX version used in the ISO. Only if this file is missing in the copied ISO content, it has to be cut out of the original ISO image file, before above xorriso run is performed:
$ dd if=/path/to/archISO bs=512 count=1 of=~/customiso/isolinux/isohdpfx.bin
If the original ISO supports bootability via EFI, this can be activated in the new ISO by inserting the following options between the lines "-isohybrid-mbr ..." and "-output ...":
-eltorito-alt-boot \ -e EFI/archiso/efiboot.img \ -no-emul-boot -isohybrid-gpt-basdat \
The file /EFI/archiso/efiboot.img is a FAT filesystem image file. If it is missing in the original ISO, then there was no EFI support in that ISO.
The newly created ISO image arch-custom.iso
is found in the home directory. You can write the ISO image to a USB stick as explained in USB Installation Media. Alternatively you can burn the ISO image on a CD, DVD, or BD with your preferred software. On Arch, that is covered in the article about burning an ISO image.
larch
larch aims to provide a more desktop-based approach, and it does not require an Arch Linux host system.
poison-livecd-creator
It is a very simple live CD creator. It uses just a Makefile to build live CD images, and uses pacman to install base and additional packages to the live CD. You can choose your packages and build them into a live CD. Moreover, it uses GRUB to boot the live CD in order to add more flexibility. This means that it is much easier to make a live USB stick without formating it. For that, you just need to install GRUB into your USB pen drive and copy the files in the ISO to your root directory in the pen drive. It relies on an Arch Linux host system and pacman.
poison-livecd-creatorAUR[broken link: archived in aur-mirror].
Linux-pf
It supports aufs among other things, making it an option for live CDs.
linux-pfAUR.