2* Documentation/filesystems/udf.txt
   4UDF Filesystem version
   6If you encounter problems with reading UDF discs using this driver,
   7please report them to, which is the
   8developer's list.
  10Write support requires a block driver which supports writing.  Currently
  11dvd+rw drives and media support true random sector writes, and so a udf
  12filesystem on such devices can be directly mounted read/write.  CD-RW
  13media however, does not support this.  Instead the media can be formatted
  14for packet mode using the utility cdrwtool, then the pktcdvd driver can
  15be bound to the underlying cd device to provide the required buffering
  16and read-modify-write cycles to allow the filesystem random sector writes
  17while providing the hardware with only full packet writes.  While not
  18required for dvd+rw media, use of the pktcdvd driver often enhances
  19performance due to very poor read-modify-write support supplied internally
  20by drive firmware.
  23The following mount options are supported:
  25        gid=            Set the default group.
  26        umask=          Set the default umask.
  27        mode=           Set the default file permissions.
  28        dmode=          Set the default directory permissions.
  29        uid=            Set the default user.
  30        bs=             Set the block size.
  31        unhide          Show otherwise hidden files.
  32        undelete        Show deleted files in lists.
  33        adinicb         Embed data in the inode (default)
  34        noadinicb       Don't embed data in the inode
  35        shortad         Use short ad's
  36        longad          Use long ad's (default)
  37        nostrict        Unset strict conformance
  38        iocharset=      Set the NLS character set
  40The uid= and gid= options need a bit more explaining.  They will accept a
  41decimal numeric value which will be used as the default ID for that mount.
  42They will also accept the string "ignore" and "forget".  For files on the disk
  43that are owned by nobody ( -1 ), they will instead look as if they are owned
  44by the default ID.  The ignore option causes the default ID to override all
  45IDs on the disk, not just -1.  The forget option causes all IDs to be written
  46to disk as -1, so when the media is later remounted, they will appear to be
  47owned by whatever default ID it is mounted with at that time.
  49For typical desktop use of removable media, you should set the ID to that
  50of the interactively logged on user, and also specify both the forget and
  51ignore options.  This way the interactive user will always see the files
  52on the disk as belonging to him.
  54The remaining are for debugging and disaster recovery:
  56        novrs           Skip volume sequence recognition 
  58The following expect a offset from 0.
  60        session=        Set the CDROM session (default= last session)
  61        anchor=         Override standard anchor location. (default= 256)
  62        volume=         Override the VolumeDesc location. (unused)
  63        partition=      Override the PartitionDesc location. (unused)
  64        lastblock=      Set the last block of the filesystem/
  66The following expect a offset from the partition root.
  68        fileset=        Override the fileset block location. (unused)
  69        rootdir=        Override the root directory location. (unused)
  70                        WARNING: overriding the rootdir to a non-directory may
  71                                yield highly unpredictable results.
  75For the latest version and toolset see:
  78Documentation on UDF and ECMA 167 is available FREE from:
  82Ben Fennema <>