Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 139 insertions, 0 deletions

diff --git a/Documentation/cdrom/packet-writing.rst b/Documentation/cdrom/packet-writing.rst
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+==============
+Packet writing
+==============
+
+Getting started quick
+---------------------
+
+- Select packet support in the block device section and UDF support in
+  the file system section.
+
+- Compile and install kernel and modules, reboot.
+
+- You need the udftools package (pktsetup, mkudffs, cdrwtool).
+  Download from https://github.com/pali/udftools
+
+- Grab a new CD-RW disc and format it (assuming CD-RW is hdc, substitute
+  as appropriate)::
+
+	# cdrwtool -d /dev/hdc -q
+
+- Setup your writer::
+
+	# pktsetup dev_name /dev/hdc
+
+- Now you can mount /dev/pktcdvd/dev_name and copy files to it. Enjoy::
+
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD-RW media
+-------------------------------
+
+DVD-RW discs can be written to much like CD-RW discs if they are in
+the so called "restricted overwrite" mode. To put a disc in restricted
+overwrite mode, run::
+
+	# dvd+rw-format /dev/hdc
+
+You can then use the disc the same way you would use a CD-RW disc::
+
+	# pktsetup dev_name /dev/hdc
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD+RW media
+-------------------------------
+
+According to the DVD+RW specification, a drive supporting DVD+RW discs
+shall implement "true random writes with 2KB granularity", which means
+that it should be possible to put any filesystem with a block size >=
+2KB on such a disc. For example, it should be possible to do::
+
+	# dvd+rw-format /dev/hdc   (only needed if the disc has never
+	                            been formatted)
+	# mkudffs /dev/hdc
+	# mount /dev/hdc /cdrom -t udf -o rw,noatime
+
+However, some drives don't follow the specification and expect the
+host to perform aligned writes at 32KB boundaries. Other drives do
+follow the specification, but suffer bad performance problems if the
+writes are not 32KB aligned.
+
+Both problems can be solved by using the pktcdvd driver, which always
+generates aligned writes::
+
+	# dvd+rw-format /dev/hdc
+	# pktsetup dev_name /dev/hdc
+	# mkudffs /dev/pktcdvd/dev_name
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD-RAM media
+--------------------------------
+
+DVD-RAM discs are random writable, so using the pktcdvd driver is not
+necessary. However, using the pktcdvd driver can improve performance
+in the same way it does for DVD+RW media.
+
+
+Notes
+-----
+
+- CD-RW media can usually not be overwritten more than about 1000
+  times, so to avoid unnecessary wear on the media, you should always
+  use the noatime mount option.
+
+- Defect management (ie automatic remapping of bad sectors) has not
+  been implemented yet, so you are likely to get at least some
+  filesystem corruption if the disc wears out.
+
+- Since the pktcdvd driver makes the disc appear as a regular block
+  device with a 2KB block size, you can put any filesystem you like on
+  the disc. For example, run::
+
+	# /sbin/mke2fs /dev/pktcdvd/dev_name
+
+  to create an ext2 filesystem on the disc.
+
+
+Using the pktcdvd sysfs interface
+---------------------------------
+
+Since Linux 2.6.20, the pktcdvd module has a sysfs interface
+and can be controlled by it. For example the "pktcdvd" tool uses
+this interface. (see http://tom.ist-im-web.de/linux/software/pktcdvd )
+
+"pktcdvd" works similar to "pktsetup", e.g.::
+
+	# pktcdvd -a dev_name /dev/hdc
+	# mkudffs /dev/pktcdvd/dev_name
+	# mount -t udf -o rw,noatime /dev/pktcdvd/dev_name /dvdram
+	# cp files /dvdram
+	# umount /dvdram
+	# pktcdvd -r dev_name
+
+
+For a description of the sysfs interface look into the file:
+
+  Documentation/ABI/testing/sysfs-class-pktcdvd
+
+
+Using the pktcdvd debugfs interface
+-----------------------------------
+
+To read pktcdvd device infos in human readable form, do::
+
+	# cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info
+
+For a description of the debugfs interface look into the file:
+
+  Documentation/ABI/testing/debugfs-pktcdvd
+
+
+
+Links
+-----
+
+See http://fy.chalmers.se/~appro/linux/DVD+RW/ for more information
+about DVD writing.