“The “Compressed Block Device” CBD, a GPL driver, is a demand
decompression block device that shrinks file system partitions 2.5
to 3 times. Imagine getting linux 2.4, glibc, Xwindows, Mozilla in
to a 16M flash! The features include writable file system,
partition management, multiple base block devices, and known file
system at reset time. The patch “cbd-2.4.0-2.patch.bz2″ contains
the kernel patch and applications to use the CBD. The offical
device major is 102 accessed using /dev/cbd/a[1-15].”
“When using the CBD only the files being used are decompressed
and in memory, this means that memory is not wasted on unused
programs and data. The big difference between CBD and any other
compressed file system is, that the whole file system is compressed
and is writable. The writes never get to the physical device. So
every time the system boots, the file system is in always the same
state.”