cramfs - Compressed RAM File System

요즘에는 잘 안쓰게 된 녀석이긴한데.. 아무튼 제약 사항은 다음과 같다.

Usage Notes ----------- File sizes are limited to less than 16MB. Maximum filesystem size is a little over 256MB.  (The last file on thefilesystem is allowed to extend past 256MB.) Only the low 8 bits of gid are stored.  The current version of mkcramfs simply truncates to 8 bits, which is a potential security issue. Hard links are supported, but hard linked files will still have a link count of 1 in the cramfs image. Cramfs directories have no `.' or `..' entries.  Directories (like every other file on cramfs) always have a link count of 1.  (There's no need to use -noleaf in `find', btw.) No timestamps are stored in a cramfs, so these default to the epoch (1970 GMT).  Recently-accessed files may have updated timestamps, but the update lasts only as long as the inode is cached in memory, after which the timestamp reverts to 1970, i.e. moves backwards in time. Currently, cramfs must be written and read with architectures of the same endianness, and can be read only by kernels with PAGE_CACHE_SIZE == 4096.  At least the latter of these is a bug, but it hasn't been decided what the best fix is.  For the moment if you have larger pages you can just change the #define in mkcramfs.c, so long as you don't mind the filesystem becoming unreadable to future kernels. [출처 : cramfs 소스중 README 파일]