1 ============== 1 ==============
2 Packet writing 2 Packet writing
3 ============== 3 ==============
4 4
5 Getting started quick 5 Getting started quick
6 --------------------- 6 ---------------------
7 7
8 - Select packet support in the block device se 8 - Select packet support in the block device section and UDF support in
9 the file system section. 9 the file system section.
10 10
11 - Compile and install kernel and modules, rebo 11 - Compile and install kernel and modules, reboot.
12 12
13 - You need the udftools package (pktsetup, mku 13 - You need the udftools package (pktsetup, mkudffs, cdrwtool).
14 Download from https://github.com/pali/udftoo 14 Download from https://github.com/pali/udftools
15 15
16 - Grab a new CD-RW disc and format it (assumin 16 - Grab a new CD-RW disc and format it (assuming CD-RW is hdc, substitute
17 as appropriate):: 17 as appropriate)::
18 18
19 # cdrwtool -d /dev/hdc -q 19 # cdrwtool -d /dev/hdc -q
20 20
21 - Setup your writer:: 21 - Setup your writer::
22 22
23 # pktsetup dev_name /dev/hdc 23 # pktsetup dev_name /dev/hdc
24 24
25 - Now you can mount /dev/pktcdvd/dev_name and 25 - Now you can mount /dev/pktcdvd/dev_name and copy files to it. Enjoy::
26 26
27 # mount /dev/pktcdvd/dev_name /cdrom - 27 # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
28 28
29 29
30 Packet writing for DVD-RW media 30 Packet writing for DVD-RW media
31 ------------------------------- 31 -------------------------------
32 32
33 DVD-RW discs can be written to much like CD-RW 33 DVD-RW discs can be written to much like CD-RW discs if they are in
34 the so called "restricted overwrite" mode. To 34 the so called "restricted overwrite" mode. To put a disc in restricted
35 overwrite mode, run:: 35 overwrite mode, run::
36 36
37 # dvd+rw-format /dev/hdc 37 # dvd+rw-format /dev/hdc
38 38
39 You can then use the disc the same way you wou 39 You can then use the disc the same way you would use a CD-RW disc::
40 40
41 # pktsetup dev_name /dev/hdc 41 # pktsetup dev_name /dev/hdc
42 # mount /dev/pktcdvd/dev_name /cdrom - 42 # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
43 43
44 44
45 Packet writing for DVD+RW media 45 Packet writing for DVD+RW media
46 ------------------------------- 46 -------------------------------
47 47
48 According to the DVD+RW specification, a drive 48 According to the DVD+RW specification, a drive supporting DVD+RW discs
49 shall implement "true random writes with 2KB g 49 shall implement "true random writes with 2KB granularity", which means
50 that it should be possible to put any filesyst 50 that it should be possible to put any filesystem with a block size >=
51 2KB on such a disc. For example, it should be 51 2KB on such a disc. For example, it should be possible to do::
52 52
53 # dvd+rw-format /dev/hdc (only neede 53 # dvd+rw-format /dev/hdc (only needed if the disc has never
54 been forma 54 been formatted)
55 # mkudffs /dev/hdc 55 # mkudffs /dev/hdc
56 # mount /dev/hdc /cdrom -t udf -o rw,n 56 # mount /dev/hdc /cdrom -t udf -o rw,noatime
57 57
58 However, some drives don't follow the specific 58 However, some drives don't follow the specification and expect the
59 host to perform aligned writes at 32KB boundar 59 host to perform aligned writes at 32KB boundaries. Other drives do
60 follow the specification, but suffer bad perfo 60 follow the specification, but suffer bad performance problems if the
61 writes are not 32KB aligned. 61 writes are not 32KB aligned.
62 62
63 Both problems can be solved by using the pktcd 63 Both problems can be solved by using the pktcdvd driver, which always
64 generates aligned writes:: 64 generates aligned writes::
65 65
66 # dvd+rw-format /dev/hdc 66 # dvd+rw-format /dev/hdc
67 # pktsetup dev_name /dev/hdc 67 # pktsetup dev_name /dev/hdc
68 # mkudffs /dev/pktcdvd/dev_name 68 # mkudffs /dev/pktcdvd/dev_name
69 # mount /dev/pktcdvd/dev_name /cdrom - 69 # mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
70 70
71 71
72 Packet writing for DVD-RAM media 72 Packet writing for DVD-RAM media
73 -------------------------------- 73 --------------------------------
74 74
75 DVD-RAM discs are random writable, so using th 75 DVD-RAM discs are random writable, so using the pktcdvd driver is not
76 necessary. However, using the pktcdvd driver c 76 necessary. However, using the pktcdvd driver can improve performance
77 in the same way it does for DVD+RW media. 77 in the same way it does for DVD+RW media.
78 78
79 79
80 Notes 80 Notes
81 ----- 81 -----
82 82
83 - CD-RW media can usually not be overwritten m 83 - CD-RW media can usually not be overwritten more than about 1000
84 times, so to avoid unnecessary wear on the m 84 times, so to avoid unnecessary wear on the media, you should always
85 use the noatime mount option. 85 use the noatime mount option.
86 86
87 - Defect management (ie automatic remapping of 87 - Defect management (ie automatic remapping of bad sectors) has not
88 been implemented yet, so you are likely to g 88 been implemented yet, so you are likely to get at least some
89 filesystem corruption if the disc wears out. 89 filesystem corruption if the disc wears out.
90 90
91 - Since the pktcdvd driver makes the disc appe 91 - Since the pktcdvd driver makes the disc appear as a regular block
92 device with a 2KB block size, you can put an 92 device with a 2KB block size, you can put any filesystem you like on
93 the disc. For example, run:: 93 the disc. For example, run::
94 94
95 # /sbin/mke2fs /dev/pktcdvd/dev_name 95 # /sbin/mke2fs /dev/pktcdvd/dev_name
96 96
97 to create an ext2 filesystem on the disc. 97 to create an ext2 filesystem on the disc.
98 98
99 99
100 Using the pktcdvd sysfs interface 100 Using the pktcdvd sysfs interface
101 --------------------------------- 101 ---------------------------------
102 102
103 Since Linux 2.6.20, the pktcdvd module has a s 103 Since Linux 2.6.20, the pktcdvd module has a sysfs interface
104 and can be controlled by it. For example the " 104 and can be controlled by it. For example the "pktcdvd" tool uses
105 this interface. (see http://tom.ist-im-web.de/ 105 this interface. (see http://tom.ist-im-web.de/linux/software/pktcdvd )
106 106
107 "pktcdvd" works similar to "pktsetup", e.g.:: 107 "pktcdvd" works similar to "pktsetup", e.g.::
108 108
109 # pktcdvd -a dev_name /dev/hdc 109 # pktcdvd -a dev_name /dev/hdc
110 # mkudffs /dev/pktcdvd/dev_name 110 # mkudffs /dev/pktcdvd/dev_name
111 # mount -t udf -o rw,noatime /dev/pktc 111 # mount -t udf -o rw,noatime /dev/pktcdvd/dev_name /dvdram
112 # cp files /dvdram 112 # cp files /dvdram
113 # umount /dvdram 113 # umount /dvdram
114 # pktcdvd -r dev_name 114 # pktcdvd -r dev_name
115 115
116 116
117 For a description of the sysfs interface look 117 For a description of the sysfs interface look into the file:
118 118
119 Documentation/ABI/testing/sysfs-class-pktcdv 119 Documentation/ABI/testing/sysfs-class-pktcdvd
120 120
121 121
122 Using the pktcdvd debugfs interface 122 Using the pktcdvd debugfs interface
123 ----------------------------------- 123 -----------------------------------
124 124
125 To read pktcdvd device infos in human readable 125 To read pktcdvd device infos in human readable form, do::
126 126
127 # cat /sys/kernel/debug/pktcdvd/pktcdv 127 # cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info
128 128
129 For a description of the debugfs interface loo 129 For a description of the debugfs interface look into the file:
130 130
131 Documentation/ABI/testing/debugfs-pktcdvd 131 Documentation/ABI/testing/debugfs-pktcdvd
132 132
133 133
134 134
135 Links 135 Links
136 ----- 136 -----
137 137
138 See http://fy.chalmers.se/~appro/linux/DVD+RW/ 138 See http://fy.chalmers.se/~appro/linux/DVD+RW/ for more information
139 about DVD writing. 139 about DVD writing.
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