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Based on kernel version 3.9. Page generated on 2013-05-02 23:06 EST.

	USING VFAT
	----------------------------------------------------------------------
	To use the vfat filesystem, use the filesystem type 'vfat'.  i.e.
	  mount -t vfat /dev/fd0 /mnt
	
	No special partition formatter is required.  mkdosfs will work fine
	if you want to format from within Linux.
	
	VFAT MOUNT OPTIONS
	----------------------------------------------------------------------
	uid=###       -- Set the owner of all files on this filesystem.
			 The default is the uid of current process.
	
	gid=###       -- Set the group of all files on this filesystem.
			 The default is the gid of current process.
	
	umask=###     -- The permission mask (for files and directories, see umask(1)).
	                 The default is the umask of current process.
	
	dmask=###     -- The permission mask for the directory.
	                 The default is the umask of current process.
	
	fmask=###     -- The permission mask for files.
	                 The default is the umask of current process.
	
	allow_utime=### -- This option controls the permission check of mtime/atime.
	
	                  20 - If current process is in group of file's group ID,
	                       you can change timestamp.
	                   2 - Other users can change timestamp.
	
	                 The default is set from `dmask' option. (If the directory is
	                 writable, utime(2) is also allowed. I.e. ~dmask & 022)
	
	                 Normally utime(2) checks current process is owner of
	                 the file, or it has CAP_FOWNER capability.  But FAT
	                 filesystem doesn't have uid/gid on disk, so normal
	                 check is too unflexible. With this option you can
	                 relax it.
	
	codepage=###  -- Sets the codepage number for converting to shortname
			 characters on FAT filesystem.
			 By default, FAT_DEFAULT_CODEPAGE setting is used.
	
	iocharset=<name> -- Character set to use for converting between the
			 encoding is used for user visible filename and 16 bit
			 Unicode characters. Long filenames are stored on disk
			 in Unicode format, but Unix for the most part doesn't
			 know how to deal with Unicode.
			 By default, FAT_DEFAULT_IOCHARSET setting is used.
	
			 There is also an option of doing UTF-8 translations
			 with the utf8 option.
	
			 NOTE: "iocharset=utf8" is not recommended. If unsure,
			 you should consider the following option instead.
	
	utf8=<bool>   -- UTF-8 is the filesystem safe version of Unicode that
			 is used by the console.  It can be enabled for the
			 filesystem with this option. If 'uni_xlate' gets set,
			 UTF-8 gets disabled.
	
	uni_xlate=<bool> -- Translate unhandled Unicode characters to special
			 escaped sequences.  This would let you backup and
			 restore filenames that are created with any Unicode
			 characters.  Until Linux supports Unicode for real,
			 this gives you an alternative.  Without this option,
			 a '?' is used when no translation is possible.  The
			 escape character is ':' because it is otherwise
			 illegal on the vfat filesystem.  The escape sequence
			 that gets used is ':' and the four digits of hexadecimal
			 unicode.
	
	nonumtail=<bool> -- When creating 8.3 aliases, normally the alias will
	                 end in '~1' or tilde followed by some number.  If this
	                 option is set, then if the filename is 
	                 "longfilename.txt" and "longfile.txt" does not
	                 currently exist in the directory, 'longfile.txt' will
	                 be the short alias instead of 'longfi~1.txt'. 
	                  
	usefree       -- Use the "free clusters" value stored on FSINFO. It'll
	                 be used to determine number of free clusters without
	                 scanning disk. But it's not used by default, because
	                 recent Windows don't update it correctly in some
	                 case. If you are sure the "free clusters" on FSINFO is
	                 correct, by this option you can avoid scanning disk.
	
	quiet         -- Stops printing certain warning messages.
	
	check=s|r|n   -- Case sensitivity checking setting.
	                 s: strict, case sensitive
	                 r: relaxed, case insensitive
	                 n: normal, default setting, currently case insensitive
	
	nocase        -- This was deprecated for vfat. Use shortname=win95 instead.
	
	shortname=lower|win95|winnt|mixed
		      -- Shortname display/create setting.
			 lower: convert to lowercase for display,
				emulate the Windows 95 rule for create.
			 win95: emulate the Windows 95 rule for display/create.
			 winnt: emulate the Windows NT rule for display/create.
			 mixed: emulate the Windows NT rule for display,
				emulate the Windows 95 rule for create.
			 Default setting is `mixed'.
	
	tz=UTC        -- Interpret timestamps as UTC rather than local time.
	                 This option disables the conversion of timestamps
	                 between local time (as used by Windows on FAT) and UTC
	                 (which Linux uses internally).  This is particularly
	                 useful when mounting devices (like digital cameras)
	                 that are set to UTC in order to avoid the pitfalls of
	                 local time.
	time_offset=minutes
		      -- Set offset for conversion of timestamps from local time
			 used by FAT to UTC. I.e. <minutes> minutes will be subtracted
			 from each timestamp to convert it to UTC used internally by
			 Linux. This is useful when time zone set in sys_tz is
			 not the time zone used by the filesystem. Note that this
			 option still does not provide correct time stamps in all
			 cases in presence of DST - time stamps in a different DST
			 setting will be off by one hour.
	
	showexec      -- If set, the execute permission bits of the file will be
			 allowed only if the extension part of the name is .EXE,
			 .COM, or .BAT. Not set by default.
	
	debug         -- Can be set, but unused by the current implementation.
	
	sys_immutable -- If set, ATTR_SYS attribute on FAT is handled as
			 IMMUTABLE flag on Linux. Not set by default.
	
	flush         -- If set, the filesystem will try to flush to disk more
			 early than normal. Not set by default.
	
	rodir	      -- FAT has the ATTR_RO (read-only) attribute. On Windows,
			 the ATTR_RO of the directory will just be ignored,
			 and is used only by applications as a flag (e.g. it's set
			 for the customized folder).
	
			 If you want to use ATTR_RO as read-only flag even for
			 the directory, set this option.
	
	errors=panic|continue|remount-ro
		      -- specify FAT behavior on critical errors: panic, continue
			 without doing anything or remount the partition in
			 read-only mode (default behavior).
	
	discard       -- If set, issues discard/TRIM commands to the block
			 device when blocks are freed. This is useful for SSD devices
			 and sparse/thinly-provisoned LUNs.
	
	nfs           -- This option maintains an index (cache) of directory
			 inodes by i_logstart which is used by the nfs-related code to
			 improve look-ups.
	
			 Enable this only if you want to export the FAT filesystem
			 over NFS
	
	<bool>: 0,1,yes,no,true,false
	
	TODO
	----------------------------------------------------------------------
	* Need to get rid of the raw scanning stuff.  Instead, always use
	  a get next directory entry approach.  The only thing left that uses
	  raw scanning is the directory renaming code.
	
	
	POSSIBLE PROBLEMS
	----------------------------------------------------------------------
	* vfat_valid_longname does not properly checked reserved names.
	* When a volume name is the same as a directory name in the root
	  directory of the filesystem, the directory name sometimes shows
	  up as an empty file.
	* autoconv option does not work correctly.
	
	BUG REPORTS
	----------------------------------------------------------------------
	If you have trouble with the VFAT filesystem, mail bug reports to
	chaffee@bmrc.cs.berkeley.edu.  Please specify the filename
	and the operation that gave you trouble.
	
	TEST SUITE
	----------------------------------------------------------------------
	If you plan to make any modifications to the vfat filesystem, please
	get the test suite that comes with the vfat distribution at
	
	  http://web.archive.org/web/*/http://bmrc.berkeley.edu/
	  people/chaffee/vfat.html
	
	This tests quite a few parts of the vfat filesystem and additional
	tests for new features or untested features would be appreciated.
	
	NOTES ON THE STRUCTURE OF THE VFAT FILESYSTEM
	----------------------------------------------------------------------
	(This documentation was provided by Galen C. Hunt <gchunt@cs.rochester.edu>
	 and lightly annotated by Gordon Chaffee).
	
	This document presents a very rough, technical overview of my
	knowledge of the extended FAT file system used in Windows NT 3.5 and
	Windows 95.  I don't guarantee that any of the following is correct,
	but it appears to be so.
	
	The extended FAT file system is almost identical to the FAT
	file system used in DOS versions up to and including 6.223410239847
	:-).  The significant change has been the addition of long file names.
	These names support up to 255 characters including spaces and lower
	case characters as opposed to the traditional 8.3 short names.
	
	Here is the description of the traditional FAT entry in the current
	Windows 95 filesystem:
	
	        struct directory { // Short 8.3 names 
	                unsigned char name[8];          // file name 
	                unsigned char ext[3];           // file extension 
	                unsigned char attr;             // attribute byte 
			unsigned char lcase;		// Case for base and extension
			unsigned char ctime_ms;		// Creation time, milliseconds
			unsigned char ctime[2];		// Creation time
			unsigned char cdate[2];		// Creation date
			unsigned char adate[2];		// Last access date
			unsigned char reserved[2];	// reserved values (ignored) 
	                unsigned char time[2];          // time stamp 
	                unsigned char date[2];          // date stamp 
	                unsigned char start[2];         // starting cluster number 
	                unsigned char size[4];          // size of the file 
	        };
	
	The lcase field specifies if the base and/or the extension of an 8.3
	name should be capitalized.  This field does not seem to be used by
	Windows 95 but it is used by Windows NT.  The case of filenames is not
	completely compatible from Windows NT to Windows 95.  It is not completely
	compatible in the reverse direction, however.  Filenames that fit in
	the 8.3 namespace and are written on Windows NT to be lowercase will
	show up as uppercase on Windows 95.
	
	Note that the "start" and "size" values are actually little
	endian integer values.  The descriptions of the fields in this
	structure are public knowledge and can be found elsewhere.
	
	With the extended FAT system, Microsoft has inserted extra
	directory entries for any files with extended names.  (Any name which
	legally fits within the old 8.3 encoding scheme does not have extra
	entries.)  I call these extra entries slots.  Basically, a slot is a
	specially formatted directory entry which holds up to 13 characters of
	a file's extended name.  Think of slots as additional labeling for the
	directory entry of the file to which they correspond.  Microsoft
	prefers to refer to the 8.3 entry for a file as its alias and the
	extended slot directory entries as the file name. 
	
	The C structure for a slot directory entry follows:
	
	        struct slot { // Up to 13 characters of a long name 
	                unsigned char id;               // sequence number for slot 
	                unsigned char name0_4[10];      // first 5 characters in name 
	                unsigned char attr;             // attribute byte
	                unsigned char reserved;         // always 0 
	                unsigned char alias_checksum;   // checksum for 8.3 alias 
	                unsigned char name5_10[12];     // 6 more characters in name
	                unsigned char start[2];         // starting cluster number
	                unsigned char name11_12[4];     // last 2 characters in name
	        };
	
	If the layout of the slots looks a little odd, it's only
	because of Microsoft's efforts to maintain compatibility with old
	software.  The slots must be disguised to prevent old software from
	panicking.  To this end, a number of measures are taken:
	
	        1) The attribute byte for a slot directory entry is always set
	           to 0x0f.  This corresponds to an old directory entry with
	           attributes of "hidden", "system", "read-only", and "volume
	           label".  Most old software will ignore any directory
	           entries with the "volume label" bit set.  Real volume label
	           entries don't have the other three bits set.
	
	        2) The starting cluster is always set to 0, an impossible
	           value for a DOS file.
	
	Because the extended FAT system is backward compatible, it is
	possible for old software to modify directory entries.  Measures must
	be taken to ensure the validity of slots.  An extended FAT system can
	verify that a slot does in fact belong to an 8.3 directory entry by
	the following:
	
	        1) Positioning.  Slots for a file always immediately proceed
	           their corresponding 8.3 directory entry.  In addition, each
	           slot has an id which marks its order in the extended file
	           name.  Here is a very abbreviated view of an 8.3 directory
	           entry and its corresponding long name slots for the file
	           "My Big File.Extension which is long":
	
	                <proceeding files...>
	                <slot #3, id = 0x43, characters = "h is long">
	                <slot #2, id = 0x02, characters = "xtension whic">
	                <slot #1, id = 0x01, characters = "My Big File.E">
	                <directory entry, name = "MYBIGFIL.EXT">
	
	           Note that the slots are stored from last to first.  Slots
	           are numbered from 1 to N.  The Nth slot is or'ed with 0x40
	           to mark it as the last one.
	
	        2) Checksum.  Each slot has an "alias_checksum" value.  The
	           checksum is calculated from the 8.3 name using the
	           following algorithm:
	
	                for (sum = i = 0; i < 11; i++) {
	                        sum = (((sum&1)<<7)|((sum&0xfe)>>1)) + name[i]
	                }
	
		3) If there is free space in the final slot, a Unicode NULL (0x0000) 
		   is stored after the final character.  After that, all unused 
		   characters in the final slot are set to Unicode 0xFFFF.
	
	Finally, note that the extended name is stored in Unicode.  Each Unicode
	character takes two bytes.

• [ filesystems ]
• 00-INDEX
• 9p.txt
• adfs.txt
• affs.txt
• afs.txt
• autofs4-mount-control.txt
• automount-support.txt
• befs.txt
• bfs.txt
• btrfs.txt
• [ caching ]
• ceph.txt
• cifs.txt
• coda.txt
• [ configfs ]
• cramfs.txt
• debugfs.txt
• devpts.txt
• directory-locking
• dlmfs.txt
• dnotify.txt
• dnotify_test.c
• ecryptfs.txt
• efivarfs.txt
• exofs.txt
• ext2.txt
• ext3.txt
• ext4.txt
• f2fs.txt
• fiemap.txt
• files.txt
• fuse.txt
• gfs2-glocks.txt
• gfs2-uevents.txt
• gfs2.txt
• hfs.txt
• hfsplus.txt
• hpfs.txt
• inotify.txt
• isofs.txt
• jfs.txt
• Locking
• locks.txt
• logfs.txt
• Makefile
• mandatory-locking.txt
• ncpfs.txt
• [ nfs ]
• nilfs2.txt
• ntfs.txt
• ocfs2.txt
• omfs.txt
• path-lookup.txt
• [ pohmelfs ]
• porting
• proc.txt
• qnx6.txt
• quota.txt
• ramfs-rootfs-initramfs.txt
• relay.txt
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• seq_file.txt
• sharedsubtree.txt
• spufs.txt
• squashfs.txt
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• sysfs-tagging.txt
• sysfs.txt
• sysv-fs.txt
• tmpfs.txt
• ubifs.txt
• udf.txt
• ufs.txt
• vfat.txt
• vfs.txt
• xfs-delayed-logging-design.txt
• xfs.txt
• xip.txt
•