GUI Tab: Preparing the Medium

This tab presents the various possibilities for installing the live system that was built on the 'larchify' tab onto a bootable device, which can be in iso9660 form (to burn to a CD/DVD), or a partition on a hard disk or flash storage device. A suitable bootloader can also be installed.

Bootloader

The choice between GRUB ('legacy') and syslinux/isolinux is provided. Editing their configuration files is covered on the 'Medium Profile' tab. Whenever a 'larch source' is selected, the validity of this source is tested, along with bootloader availability, so it could turn out (according to the nature of the source), that one - or even both - of the bootloaders is not available. To support a particular bootloader the corresponding package must be installed in the larchified system.

Selecting the source

In the 'normal' case this will be the first (default) option, the larchified system. The other choices enable copying of an already existing larch live medium (or building a boot CD for a USB medium). If no larchified system has been built yet, a warning will pop up and the build buttons will be disabled.

Copying an existing larch live medium

The other source options allow the system to be taken from one that has already been built. This could be useful for copying from CD to USB stick, or vice versa, or for copies which involve changes to an option or two. The 'Device' source requires an unmounted partition (if you're using some sort of automounting, you'll have to sort that out yourself). The 'iso file' source allows you to select an 'iso' image (ending '.iso') anywhere in the file-system. The 'Path' source allows you to select a directory within the filesystem. If you want to use a CD/DVD as source, mount it and use this option to navigate to the mount point.

Note that whenever a new source is selected a check is run on it, to check whether it could be valid and to determine one or two attributes (e.g. available bootloaders).

Build an iso, for CD or DVD

Only limited customization possibilities are offered here, you can set the volume label ('-V' option to mkisofs) and select from the available bootloaders. The only option for medium detection is 'Search (for larchboot)', described below.

Install to partitition

Here one must select the partition to install to - which must be plugged in and not mounted (again, good luck to automounters), and also select how the live initramfs is to find the correct partition. The available options are:

  • Partition: The device will be sought on the basis of its (current) device name - such as /dev/sdb1. This is only suitable if you can be sure the device will always get the same name (which - especially with pluggable devices - is unlikely).
  • UUID: Each device normally has a unique UUID, so this is a pretty reliable method. It's just that the UUIDs themselves are rather ungainly and unmemorable.
  • LABEL: Booting on the basis of the device label can be quite reliable and quite readable, so it might be a good compromise.
  • Search (for larchboot): The live initramfs tests all visible devices until it finds one containing the file larch/larchboot.

The choice of bootloader will determine the file-system with which the partition is formatted - for syslinux 'vfat' is used, for GRUB 'ext2'. No other file-system types are supported at present. There is also an option to install the live system without first formatting the partition. This might be useful in certain very special cases but it is generally not recommended. Another option for experts only is to suppress the installation of the bootloader. The bootloader is always installed to the Master Boot Record of the live medium, which might not always be desirable, so an installation without this step is also supported.

With the button 'Enable session-saving', you can determine whether the medium gets a file 'larch/save', which is needed to enable the session saving feature (this option overrides the profile's nosave suggestion).

The option 'Not bootable via search' suppresses the generation of the 'larch/larchboot' file, so that the method of medium detection which searches for this file will not work on the generated medium (this of course makes no sense if the 'Search (for larchboot)' medium detection method is selected for this medium).

Volume label

The maximum length of the label should be 16 characters, which is ok for 'iso' (CD/DVD) and for 'ext2' (GRUB on partition), but 'vfat' (syslinux on partition) only accepts 11.

Write the larch medium

When enough information is available, this button will be enabled and the generation can be started. If an 'iso' file is to be generated, a pop-up file-save dialog appears so that the destination can be specified.

Create boot iso

If a 'device' (partition) is selected as 'larch source', there is the possibility of generating a boot CD for this live medium. This is to cover cases where a machine cannot boot from USB devices, but can boot from a CD. Just the kernel, initramfs and bootloader are put in the boot iso. The live system's initramfs will (hopefully) then be able to find the actual live medium. The detection method can be selected, and it need not be the same as that which the live medium itself uses. Note that the USB device for which the CD is to be generated must be plugged in (not mounted) and selected in the device chooser.

A pop-up file-save dialog appears so that the destination can be specified. Note that the boot iso does not get the volume label shown in the gui (that is for complete larch media), the default generated by the back-end script 'boot_iso.py' is used.

Use chroot

To increase portability and reduce demands on the build system, most of the fancy processing can be done using the system which was installed for larchification, via chroot. For normal installation and building of a larch system this is the default, but when using one of the other sources (for copying etc.) this approach is not used by default - for the simple reason that there may well not be a suitable chroot system available. The gui offers the possibility of overriding this, so that if you do indeed have a suitable chroot system, then you can use it if you want. It is also possible to disable chrooting for the normal case, but I'm not sure how useful this option is.

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