The squashfs filesystem existed as a kernel patch for a long time, eventually being merged into mainline Linux. It is very easy to use:
You create a filesystem image using mksquashfs and install it to the flash memory:
$ mksquashfs rootfs rootfs.squashfsThe resulting filesystem is read-only, so there is no mechanism to modify any of the files at runtime. The only way to update a squashfs filesystem is to erase the whole partition and program in a new image.
Squashfs is not bad-block aware and so must be used with reliable flash memory such as NOR flash. However, it can be used on NAND flash as long as you use UBI to create an emulated, …