Re: Migrations to xorriso

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Isaac Dupree wrote:
> What size range are the whole images? 

The minimum output of grub-mkrescue 1.98 with
xorriso is 1544192 bytes.
grub-mkisofs: 1550336
genisoimage:  1859584 (-307200 with -no-pad)

One may add lots of other files, of course.


> Also I guess no one compresses whole ISOs

It makes few sense to compress the ISO as a
whole. But one could compress some files in it.

One could implement a reader for H. Peter Anvin's
zisofs format in GRUB's ISO 9660 reader - if not
present already.
zisofs is a transparent content compression of
single files. A reader is implemented in the
Linux kernel. See macro CONFIG_ZISOFS in
fs/isofs/*.[ch].
An authorised description is given in
doc/zisofs_format.txt of xorriso resp. in
  http://bazaar.launchpad.net/~libburnia-team/libisofs/scdbackup/annotate/head:/doc/zisofs_format.txt
The ISO 9660 directory tree stays uncompressed.
Compressed and uncompressed files can be mixed.

xorriso can produce zisofs compressed data files
on the fly (needs zlib).
A grub-mkrescue 1.98 image with all files
compressed has 884736 bytes. But one would have
to leave those files uncompressed which are
needed for reading ISO 9660 and zisofs
compression.

Have a nice day :)

Thomas