linux/Documentation/cdrom/packet-writing.txt
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   1Getting started quick
   2---------------------
   3
   4- Select packet support in the block device section and UDF support in
   5  the file system section.
   6
   7- Compile and install kernel and modules, reboot.
   8
   9- You need the udftools package (pktsetup, mkudffs, cdrwtool).
  10  Download from http://sourceforge.net/projects/linux-udf/
  11
  12- Grab a new CD-RW disc and format it (assuming CD-RW is hdc, substitute
  13  as appropriate):
  14        # cdrwtool -d /dev/hdc -q
  15
  16- Setup your writer
  17        # pktsetup dev_name /dev/hdc
  18
  19- Now you can mount /dev/pktcdvd/dev_name and copy files to it. Enjoy!
  20        # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
  21
  22
  23Packet writing for DVD-RW media
  24-------------------------------
  25
  26DVD-RW discs can be written to much like CD-RW discs if they are in
  27the so called "restricted overwrite" mode. To put a disc in restricted
  28overwrite mode, run:
  29
  30        # dvd+rw-format /dev/hdc
  31
  32You can then use the disc the same way you would use a CD-RW disc:
  33
  34        # pktsetup dev_name /dev/hdc
  35        # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
  36
  37
  38Packet writing for DVD+RW media
  39-------------------------------
  40
  41According to the DVD+RW specification, a drive supporting DVD+RW discs
  42shall implement "true random writes with 2KB granularity", which means
  43that it should be possible to put any filesystem with a block size >=
  442KB on such a disc. For example, it should be possible to do:
  45
  46        # dvd+rw-format /dev/hdc   (only needed if the disc has never
  47                                    been formatted)
  48        # mkudffs /dev/hdc
  49        # mount /dev/hdc /cdrom -t udf -o rw,noatime
  50
  51However, some drives don't follow the specification and expect the
  52host to perform aligned writes at 32KB boundaries. Other drives do
  53follow the specification, but suffer bad performance problems if the
  54writes are not 32KB aligned.
  55
  56Both problems can be solved by using the pktcdvd driver, which always
  57generates aligned writes.
  58
  59        # dvd+rw-format /dev/hdc
  60        # pktsetup dev_name /dev/hdc
  61        # mkudffs /dev/pktcdvd/dev_name
  62        # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
  63
  64
  65Packet writing for DVD-RAM media
  66--------------------------------
  67
  68DVD-RAM discs are random writable, so using the pktcdvd driver is not
  69necessary. However, using the pktcdvd driver can improve performance
  70in the same way it does for DVD+RW media.
  71
  72
  73Notes
  74-----
  75
  76- CD-RW media can usually not be overwritten more than about 1000
  77  times, so to avoid unnecessary wear on the media, you should always
  78  use the noatime mount option.
  79
  80- Defect management (ie automatic remapping of bad sectors) has not
  81  been implemented yet, so you are likely to get at least some
  82  filesystem corruption if the disc wears out.
  83
  84- Since the pktcdvd driver makes the disc appear as a regular block
  85  device with a 2KB block size, you can put any filesystem you like on
  86  the disc. For example, run:
  87
  88        # /sbin/mke2fs /dev/pktcdvd/dev_name
  89
  90  to create an ext2 filesystem on the disc.
  91
  92
  93Using the pktcdvd sysfs interface
  94---------------------------------
  95
  96Since Linux 2.6.20, the pktcdvd module has a sysfs interface
  97and can be controlled by it. For example the "pktcdvd" tool uses
  98this interface. (see http://tom.ist-im-web.de/download/pktcdvd )
  99
 100"pktcdvd" works similar to "pktsetup", e.g.:
 101
 102        # pktcdvd -a dev_name /dev/hdc
 103        # mkudffs /dev/pktcdvd/dev_name
 104        # mount -t udf -o rw,noatime /dev/pktcdvd/dev_name /dvdram
 105        # cp files /dvdram
 106        # umount /dvdram
 107        # pktcdvd -r dev_name
 108
 109
 110For a description of the sysfs interface look into the file:
 111
 112  Documentation/ABI/testing/sysfs-class-pktcdvd
 113
 114
 115Using the pktcdvd debugfs interface
 116-----------------------------------
 117
 118To read pktcdvd device infos in human readable form, do:
 119
 120        # cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info
 121
 122For a description of the debugfs interface look into the file:
 123
 124  Documentation/ABI/testing/debugfs-pktcdvd
 125
 126
 127
 128Links
 129-----
 130
 131See http://fy.chalmers.se/~appro/linux/DVD+RW/ for more information
 132about DVD writing.
 133
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