Hi, i'm the developer of xorriso. (Cc me, please)
Joey Hess wrote: > Assuming debian-cd does > switch to xorriso, so after it supports jidgo We should begin to write down an exact specification of the jigdo files which xorriso shall produce during the run by which it generates an ISO image. (Shall it generate a ready-to-mount image at all ?) I did read http://atterer.org/jigdo/debian-jigdo-mini-howto#HOWJIGDOWORKS and believe to understand the principles. I assume that xorriso shall act like jigdo-file and produce at least the .template file. Is there a byte-by-byte specification of its format ? What about the .jigdo file ? Is it prepared by a different tool ? Shall xorriso produce parts of it ? Or shall xorriso read it in order to learn which files are known ? > I would caution that my idea of adding a partition for firmware is > potentially half-baked. It matches well the idea behind the partition table entries of isohybrid and grub-mkrescue. Both have their partition table to reserve the space of the ISO image and to give partition editors a hint about the unused space on the device. So to populate the image with more partitions seems straightforward. > The same problem could be > solved more generally by eg, using multisession to append the firmware > to the iso. But that would require the user run a script; xorriso makes it quite easy to add sessions. But it is not widely in use. The size overhead of adding a session depends much on the number of files in the resulting ISO image. Each session gets a new copy of the whole directory tree. (E.g. 45000 files = 15 MB in my backup.) > the firmware > parition does allow even a user limited to Windows and no extra programs > to add firmware to their USB stick Yeah. People expect their USB sticks to have mountable partitions. A flat stick with ISO image is sometimes frowned at. Currently isohybrid and grub-mkrescue bear still quite unusual partition layouts: - isohybrid partition starts at block 0. I.e. there is no unclaimed space before the first partition. - grub-mkrescue partition starts at block 1. This one is not mountable. Your idea goes well with my current development work: A partition with non-zero start block address but nevertheless mountable. (Needs two superblocks and two directory trees.) Put together i now imagine this partition layout: 0 kB - 32 kB Unclaimed space before partition. Playground for boot loaders. 32 kB - X kB First partition covering the rest of the ISO image up to the start of the appended FAT image X kB - Z kB Second partition covering the FAT image The ISO image would believe to reach from 0 kB to Z kB. So the FAT partition would be safe from partition editors and from ISO multi-session. The USB stick would appear on GNU/Linux as /dev/sdb ISO filesystem. (This one is seen on CD, or when booting via isohybrid MBR or via GRUB MBR.) /dev/sdb1 ISO filesystem with same content /dev/sdb2 FAT filesystem This brings some size overhead in comparison to simpler layouts. But it should be quite self-explaining to any system and user. Have a nice day :) Thomas -- To UNSUBSCRIBE, email to debian-cd-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/94312122832...@192.168.2.69