Chapter 6. Making a Bootable LRP CDROM

Table of Contents

Important Considerations
Creating a CDROM Boot Image
Getting Packages From CDROM

Important Considerations

There are many things to consider in creating a bootable CDROM using LRP.

  • Packages cannot be loaded from the boot medium, since the boot medium is a floppy disk image artificially loaded into memory via PC BIOS INT 13. Only syslinux, the Linux kernel, and root.lrp (the root filesystem loaded by the Linux kernel) are available.

  • Packages might be stored on the CDROM in a directory. It must be determined if the LRP variant used supports access to packages in directories.

  • The configuration files on the boot disk are fixed and unchangeable. To permit changeable configurations, access to a real floppy is required.

These considerations must be taken into account when creating a bootable CDROM.

Creating a CDROM Boot Image

A disk image used by a bootable (El Torrito) CDROM is accessed via the BIOS INT 13. Currently, there is no device driver for Linux to support such a device; this means that once root.lrp is loaded, the system has no access to the disk image. Thus, no packages can be loaded from this boot disk image, et al. Another method has to be found to load packages into a bootable LRP CDROM. There seem to be two ways of doing this:

  1. Install packages to be loaded to the root level of the CDROM

    Discussion: This means that there will be many packages in the root directory. In my opinion, this makes for a messy directory, and confuses anyone relying on the CDROM.

  2. Load all packages into root.lrp.

    Discussion: Personally, this doesn’t seem to be the best either. However, I like it better, because it keeps the CDROM clean and allows all of the packages to be loaded without any fuss. With apkg, packages can be removed if desired. The swelled root.lrp does, however, require more disk space to load.

  3. Load packages over the network.

    Discussion: This is an attractive idea, since then the packages can be loaded from any system but no disks need be carried.

  4. Load packages from a list of packages in a file.

    Discussion: This is also a good idea. This has the potential of allowing the loading of packages from CDROM while maintaining the actual configuration on a separate disk somewhere.

Getting Packages From CDROM

Getting packages loaded from the CDROM presents somewhat of a problem, since it is unclear as to what the device filename of the CDROM will be. This can be gotten around by automatically creating a file /dev/cdrom and using this. This also permits the CDROM to be loaded from using an arbitrary boot diskette.

Would it also be a good idea to mount the boot disk image as /dev/cdboot? It is not clear if there is a way to determine if a CDROM is bootable, and if so, what the image name is. More examination is needed.

Loading packages from /dev/cdrom would require, at minimum, leaving packages in the root directory. If packages are stored in other directories, then the directory must be specified in the LRP parameter or in a file.

If the file containing a list of packages to load is on the CDROM, then the flexibility is greatly reduced as the configurations available are limited to the files found on disk.