Re: GuixSD bootable ISO-9669 image (was: Re: GuixSD on servers [Fwd: [rtracker.1984.is #131647] A question about VServer system specific requirements])

[Danny Milosavljevic <dannym@scratchpost.org>]

>... -V gnu-disk-image /mnt/disk-image-partition-1.
> xorriso : WARNING : -volid text does not comply to ISO 9660 / ECMA 119 rules

That's because all characters in an ISO 9660 volume identification need to be one of "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_".

If you use more complicated labels you additionally need to support an extension like Joliet (which provides its own seperate directory tree in addition to the one of ISO 9660!).  It's easier to use uppercase letters only and not have a second tree.

See <http://wiki.osdev.org/ISO_9660>.

That page also describes how the disklabel looks:
- The first 32 KiB contain some non-ISO9660 stuff - it might be misdetected as something non-ISO9660 if you take it seriously.  So skip that.
- A sector has 2 KiB.
- The volume descriptors start at sector 16.
- There can be multiple volume descriptors.
- Each volume descriptor is one sector long.
- A volume descriptor can be either a boot record, a primary volume descriptor, a supplementary volume descriptor (for Joliet), a volume partition descriptor, or a volume descriptor set terminator.
- The list of volume descriptors have to be terminated by a volume descriptor set terminator.

- The primary volume descriptor contains the volume identifier at offset 40, length 32 Byte.

See also <http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-119.pdf>.