mkksiso¶

Authors:: Brian C. Lane <bcl@redhat.com>

mkksiso is a tool for creating kickstart boot isos. In it's simplest form you can add a kickstart to a boot.iso and the kickstart will be executed when the iso is booted. If the original iso was created with EFI and Mac support the kickstart boot.iso will include this support as well.

mkksiso The host system architecture needs to match that of the iso. mkksiso will raise an error if it finds a .discinfo on the iso with a mismatched arch.

As of version 38.4 mkksiso needs to be run as root to create a fully bootable iso. Booting on a UEFI system with the iso written to a flash drive requires updating the config files in the embedded efiboot image in the iso. If you do not need this functionality you can still run it as a user by passing --skip-mkefiboot.

mkksiso cmdline arguments¶

Add a kickstart and files to an iso

usage: mkksiso [-h] [-a ADD_PATHS] [-c CMDLINE] [-r ARGS] [--debug] [--no-md5sum] [--ks KICKSTART]
               [-V VOLID] [--skip-mkefiboot]
               [KICKSTART] input_iso output_iso

Positional Arguments¶

KICKSTART: Optional kickstart to add to the ISO
input_iso: ISO to modify
output_iso: Full pathname of iso to be created

Named Arguments¶

-a, --add

File or directory to add to ISO (may be used multiple times)

Default: []

-c, --cmdline

Arguments to add to kernel cmdline

Default: ""

-r, --rm-args

Space separated list of arguments to remove from the kernel cmdline

Default: ""

--debug

print debugging info

Default: 20

--no-md5sum

Do not run implantisomd5 on the ouput iso

Default: True

--ks

Optional kickstart to add to the ISO

-V, --volid

Set the ISO volume id, defaults to input's

--skip-mkefiboot

Skip running mkefiboot

Default: False

Create a kickstart boot.iso or DVD¶

Create a kickstart like you normally would, kickstart documentation can be found here, including the url and repo commands. If you are creating a DVD and only need the content on the DVD you can use the cdrom command to install without a network connection. Then run mkksiso like this:

mkksiso --ks /PATH/TO/KICKSTART /PATH/TO/ISO /PATH/TO/NEW-ISO

This will create a new iso with the kickstart in the root directory, and the kernel cmdline will have inst.ks=... added to it so that it will be executed when the iso is booted (be careful not to boot on a system you don't want to wipe out! There will be no prompting).

By default the volume id of the iso is preserved. You can set a custom volid by passing -V and the string to set. The kernel cmdline will be changes, and the iso will have th custom volume id.

eg.:

mkksiso -V "Test Only" --ks /PATH/TO/KICKSTART /PATH/TO/ISO /PATH/TO/NEW-ISO

Adding package repos to a boot.iso¶

You can add repo directories to the iso using --add /PATH/TO/REPO/, make sure it contains the repodata directory by running createrepo_c on it first. In the kickstart you can refer to the directories (and files) on the iso using file:///run/install/repo/DIRECTORY/. You can then use these repos in the kickstart like this:

repo --name=extra-repo --baseurl=file:///run/install/repo/extra-repo/

Run mkksiso like so:

mkksiso --add /PATH/TO/REPO/ --ks /PATH/TO/KICKSTART /PATH/TO/ISO /PATH/TO/NEW-ISO

Create a liveimg boot.iso¶

You can use the kickstart liveimg command, to install a pre-generated disk image or tar to the system the iso is booting on.

Create a disk image or tar with osbuild-composer or livemedia-creator, make sure the image includes tools expected by anaconda, as well as the kernel and bootloader support. In osbuild-composer use the tar image type and make sure to include the kernel, grub2, and grub2-tools packages. If you plan to install it to a UEFI machine make sure to include grub2-efi and efibootmgr in the blueprint.

Add the root.tar.xz file to the iso using --add /PATH/TO/ROOT.TAR.XZ, and in the kickstart reference it with the liveimg command like this:

liveimg --url=file:///run/install/repo/root.tar.xz

It is also a good idea to use the --checksum argument to liveimg to be sure the file hasn't been corrupted:

mkksiso --add /PATH/TO/root.tar.xz --ks /PATH/TO/KICKSTART /PATH/TO/ISO /PATH/TO/NEW-ISO

When this iso is booted it will execute the kickstart and install the liveimg contents to the system without any prompting.

Modifying kernel cmdline arguments¶

You can add arguments to the kernel cmdline in the ISO config files by using --cmdline, like this:

mkksiso --cmdline "console=ttyS0,115200n8" /PATH/TO/ISO /PATH/TO/NEW-ISO

Removing arguments¶

mkksiso version 37.3 and later support removing arguments from the cmdline. This can be done with or without adding a kickstart to the iso:

mkksiso --rm "quiet console" /PATH/TO/ISO /PATH/TO/NEW-ISO

will remove the quiet and console arguments from all the the kernel cmdlines on the ISO.

Changing existing arguments¶

With the combination of --rm and --command it is now possible to change existing arguments. For example let's say the ISO has a console=tty3 set on the cmdline. You want to change that to ttyS0 so you run this:

mkksiso --cmdline "console=ttyS0,115200n8" --rm "console" /PATH/TO/ISO /PATH/TO/NEW-ISO

which will first remove all instances of console in the config files, and then add the new console argument.

How it works¶

mkksiso only depends on xorriso and isomd5sum. It takes advantage of xorriso's ability to extract files, replace files, and add files to the iso without need to mount it.

mkksiso extracts all of the config files it knows about, and then modifies the boot configuration files to include the inst.ks command. It adds any extra command line arguments you specify, and then builds the new iso with the configuration files replaced, and new files and directories added.

The last step is to update the iso checksums so that booting with test enabled will pass. It uses implantisomd5 from the isomd5sum project.