=========================================================
ϡ
linux-2.6.26.5/Documentation/filesystems/cramfs.txt 
Ǥ
Ρ JF ץ < http://www.linux.or.jp/JF/ >
  2008/10/06
  Seiji Kaneko < skaneko at mbn dot or dot jp >
=========================================================

#	Cramfs - cram a filesystem onto a small ROM
	Cramfs -  ROM Υե륷ƥͤ碌

#cramfs is designed to be simple and small, and to compress things well.
cramfs ñǾ褯̤Ǥ褦߷פƤޤ

#It uses the zlib routines to compress a file one page at a time, and
#allows random page access.  The meta-data is not compressed, but is
#expressed in a very terse representation to make it use much less
#diskspace than traditional filesystems.
Υե륷ƥϡzlib 롼Ȥäƥե 1 ڡ˰̤
ڡǽˤƤޤ᥿ǡϰ̤Ƥޤ󤬡
ˤ̩٤ι⤤ɽˤʤäƤꡢΥե륷ƥˤ٤ƤäȾ
ʥǥ̤񤷤ޤ

#You can't write to a cramfs filesystem (making it compressible and
#compact also makes it _very_ hard to update on-the-fly), so you have to
#create the disk image with the "mkcramfs" utility.
cramfs ե륷ƥˤϽ񤭹ߤϹԤʤޤ (̲ǽǥѥȤˤ
뤳Ȥϡ¹ԻιȤƤ񤷤Ƥޤ)äơmkcramfs 桼ƥ
ƥȤäƥǥ᡼ɬפޤ

#Usage Notes
ȤΥ
------------

#File sizes are limited to less than 16MB.
ե륵 16MB ʲ¤ޤ

#Maximum filesystem size is a little over 256MB.  (The last file on the
#filesystem is allowed to extend past 256MB.)
ե륷ƥκ̤ 256MB 򾯡ĶǤ (ե륷ƥ
κǸΥե 256MB ζۤƳĥ뤳ȤǤޤ)

#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.
gid ϲ 8bit Ǽޤ󡣸ߤǤ mkcramfs ñ 8bit ؤڼ
ƤԤʤޤϥƥꥹȤʤǽޤ

#Hard links are supported, but hard linked files
#will still have a link count of 1 in the cramfs image.
ϡɥ󥯤ϥݡȤƤޤϡɥ󥯤줿ե cramfs 
Ǥ link  1 ΤޤޤǤ

#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.)
cramfs ǥ쥯ȥˤ `.'  `..' ȥϤޤ󡣥ǥ쥯ȥꡢ
 cramfs Τ٤ƤΥեΥ󥯿 1 Ǥ (ä find ʤɤ -noleaf
ȤɬפϤޤ)

#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.
cramfs ˤϥॹפϳǼƤʤᡢ (1970 GMT) ˤʤ
ƤޤǶᥢ줿եΥॹפϹƤ뤫Τ
ޤ󤬡ѹ inode ˥å夵Ƥ֤ˤȤɤޤꡢ
ϥॹפ 1970 ǯޤ (֤չԤޤ)

#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.
Ǥϡcramfs ϥǥƱƥǺɤ߽ФԤ
ɬפꡢPAGE_CACHE_SIZE  4096 Υͥ뤫ɤ߽ФǽǤ
ʤȤԤϥХȹͤƤޤνȽǤޤǤƤޤ
Ǥϡ⤷ڡ礭硢Υͥǥե륷
बɤ߽ФǤʤʤΤޤʤʤСmkcramfs.c  #define ѹ
б뤳ȤǤޤ


#For /usr/share/magic
/usr/share/magic 
---------------------

0	ulelong	0x28cd3d45	Linux cramfs offset 0
>4	ulelong	x		size %d
>8	ulelong	x		flags 0x%x
>12	ulelong	x		future 0x%x
>16	string	>\0		signature "%.16s"
>32	ulelong	x		fsid.crc 0x%x
>36	ulelong	x		fsid.edition %d
>40	ulelong	x		fsid.blocks %d
>44	ulelong	x		fsid.files %d
>48	string	>\0		name "%.16s"
512	ulelong	0x28cd3d45	Linux cramfs offset 512
>516	ulelong	x		size %d
>520	ulelong	x		flags 0x%x
>524	ulelong	x		future 0x%x
>528	string	>\0		signature "%.16s"
>544	ulelong	x		fsid.crc 0x%x
>548	ulelong	x		fsid.edition %d
>552	ulelong	x		fsid.blocks %d
>556	ulelong	x		fsid.files %d
>560	string	>\0		name "%.16s"


#Hacker Notes
ϥå
----------------

#See fs/cramfs/README for filesystem layout and implementation notes.
fs/cramfs/README ˥ե륷ƥ쥤Ȥȼ⤬ϿƤޤ
