1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
|
/*
* Ver 0.1 Nov 1 95 Pre-working code :-)
* Ver 0.2 Nov 23 95 A short backup (few megabytes) and restore procedure
* was successful ! (Using tar cvf ... on the block
* device interface).
* A longer backup resulted in major swapping, bad
* overall Linux performance and eventually failed as
* we received non serial read-ahead requests from the
* buffer cache.
* Ver 0.3 Nov 28 95 Long backups are now possible, thanks to the
* character device interface. Linux's responsiveness
* and performance doesn't seem to be much affected
* from the background backup procedure.
* Some general mtio.h magnetic tape operations are
* now supported by our character device. As a result,
* popular tape utilities are starting to work with
* ide tapes :-)
* The following configurations were tested:
* 1. An IDE ATAPI TAPE shares the same interface
* and irq with an IDE ATAPI CDROM.
* 2. An IDE ATAPI TAPE shares the same interface
* and irq with a normal IDE disk.
* Both configurations seemed to work just fine !
* However, to be on the safe side, it is meanwhile
* recommended to give the IDE TAPE its own interface
* and irq.
* The one thing which needs to be done here is to
* add a "request postpone" feature to ide.c,
* so that we won't have to wait for the tape to finish
* performing a long media access (DSC) request (such
* as a rewind) before we can access the other device
* on the same interface. This effect doesn't disturb
* normal operation most of the time because read/write
* requests are relatively fast, and once we are
* performing one tape r/w request, a lot of requests
* from the other device can be queued and ide.c will
* service all of them after this single tape request.
* Ver 1.0 Dec 11 95 Integrated into Linux 1.3.46 development tree.
* On each read / write request, we now ask the drive
* if we can transfer a constant number of bytes
* (a parameter of the drive) only to its buffers,
* without causing actual media access. If we can't,
* we just wait until we can by polling the DSC bit.
* This ensures that while we are not transferring
* more bytes than the constant referred to above, the
* interrupt latency will not become too high and
* we won't cause an interrupt timeout, as happened
* occasionally in the previous version.
* While polling for DSC, the current request is
* postponed and ide.c is free to handle requests from
* the other device. This is handled transparently to
* ide.c. The hwgroup locking method which was used
* in the previous version was removed.
* Use of new general features which are provided by
* ide.c for use with atapi devices.
* (Programming done by Mark Lord)
* Few potential bug fixes (Again, suggested by Mark)
* Single character device data transfers are now
* not limited in size, as they were before.
* We are asking the tape about its recommended
* transfer unit and send a larger data transfer
* as several transfers of the above size.
* For best results, use an integral number of this
* basic unit (which is shown during driver
* initialization). I will soon add an ioctl to get
* this important parameter.
* Our data transfer buffer is allocated on startup,
* rather than before each data transfer. This should
* ensure that we will indeed have a data buffer.
* Ver 1.1 Dec 14 95 Fixed random problems which occurred when the tape
* shared an interface with another device.
* (poll_for_dsc was a complete mess).
* Removed some old (non-active) code which had
* to do with supporting buffer cache originated
* requests.
* The block device interface can now be opened, so
* that general ide driver features like the unmask
* interrupts flag can be selected with an ioctl.
* This is the only use of the block device interface.
* New fast pipelined operation mode (currently only on
* writes). When using the pipelined mode, the
* throughput can potentially reach the maximum
* tape supported throughput, regardless of the
* user backup program. On my tape drive, it sometimes
* boosted performance by a factor of 2. Pipelined
* mode is enabled by default, but since it has a few
* downfalls as well, you may want to disable it.
* A short explanation of the pipelined operation mode
* is available below.
* Ver 1.2 Jan 1 96 Eliminated pipelined mode race condition.
* Added pipeline read mode. As a result, restores
* are now as fast as backups.
* Optimized shared interface behavior. The new behavior
* typically results in better IDE bus efficiency and
* higher tape throughput.
* Pre-calculation of the expected read/write request
* service time, based on the tape's parameters. In
* the pipelined operation mode, this allows us to
* adjust our polling frequency to a much lower value,
* and thus to dramatically reduce our load on Linux,
* without any decrease in performance.
* Implemented additional mtio.h operations.
* The recommended user block size is returned by
* the MTIOCGET ioctl.
* Additional minor changes.
* Ver 1.3 Feb 9 96 Fixed pipelined read mode bug which prevented the
* use of some block sizes during a restore procedure.
* The character device interface will now present a
* continuous view of the media - any mix of block sizes
* during a backup/restore procedure is supported. The
* driver will buffer the requests internally and
* convert them to the tape's recommended transfer
* unit, making performance almost independent of the
* chosen user block size.
* Some improvements in error recovery.
* By cooperating with ide-dma.c, bus mastering DMA can
* now sometimes be used with IDE tape drives as well.
* Bus mastering DMA has the potential to dramatically
* reduce the CPU's overhead when accessing the device,
* and can be enabled by using hdparm -d1 on the tape's
* block device interface. For more info, read the
* comments in ide-dma.c.
* Ver 1.4 Mar 13 96 Fixed serialize support.
* Ver 1.5 Apr 12 96 Fixed shared interface operation, broken in 1.3.85.
* Fixed pipelined read mode inefficiency.
* Fixed nasty null dereferencing bug.
* Ver 1.6 Aug 16 96 Fixed FPU usage in the driver.
* Fixed end of media bug.
* Ver 1.7 Sep 10 96 Minor changes for the CONNER CTT8000-A model.
* Ver 1.8 Sep 26 96 Attempt to find a better balance between good
* interactive response and high system throughput.
* Ver 1.9 Nov 5 96 Automatically cross encountered filemarks rather
* than requiring an explicit FSF command.
* Abort pending requests at end of media.
* MTTELL was sometimes returning incorrect results.
* Return the real block size in the MTIOCGET ioctl.
* Some error recovery bug fixes.
* Ver 1.10 Nov 5 96 Major reorganization.
* Reduced CPU overhead a bit by eliminating internal
* bounce buffers.
* Added module support.
* Added multiple tape drives support.
* Added partition support.
* Rewrote DSC handling.
* Some portability fixes.
* Removed ide-tape.h.
* Additional minor changes.
* Ver 1.11 Dec 2 96 Bug fix in previous DSC timeout handling.
* Use ide_stall_queue() for DSC overlap.
* Use the maximum speed rather than the current speed
* to compute the request service time.
* Ver 1.12 Dec 7 97 Fix random memory overwriting and/or last block data
* corruption, which could occur if the total number
* of bytes written to the tape was not an integral
* number of tape blocks.
* Add support for INTERRUPT DRQ devices.
* Ver 1.13 Jan 2 98 Add "speed == 0" work-around for HP COLORADO 5GB
* Ver 1.14 Dec 30 98 Partial fixes for the Sony/AIWA tape drives.
* Replace cli()/sti() with hwgroup spinlocks.
* Ver 1.15 Mar 25 99 Fix SMP race condition by replacing hwgroup
* spinlock with private per-tape spinlock.
* Ver 1.16 Sep 1 99 Add OnStream tape support.
* Abort read pipeline on EOD.
* Wait for the tape to become ready in case it returns
* "in the process of becoming ready" on open().
* Fix zero padding of the last written block in
* case the tape block size is larger than PAGE_SIZE.
* Decrease the default disconnection time to tn.
* Ver 1.16e Oct 3 99 Minor fixes.
* Ver 1.16e1 Oct 13 99 Patches by Arnold Niessen,
* niessen@iae.nl / arnold.niessen@philips.com
* GO-1) Undefined code in idetape_read_position
* according to Gadi's email
* AJN-1) Minor fix asc == 11 should be asc == 0x11
* in idetape_issue_packet_command (did effect
* debugging output only)
* AJN-2) Added more debugging output, and
* added ide-tape: where missing. I would also
* like to add tape->name where possible
* AJN-3) Added different debug_level's
* via /proc/ide/hdc/settings
* "debug_level" determines amount of debugging output;
* can be changed using /proc/ide/hdx/settings
* 0 : almost no debugging output
* 1 : 0+output errors only
* 2 : 1+output all sensekey/asc
* 3 : 2+follow all chrdev related procedures
* 4 : 3+follow all procedures
* 5 : 4+include pc_stack rq_stack info
* 6 : 5+USE_COUNT updates
* AJN-4) Fixed timeout for retension in idetape_queue_pc_tail
* from 5 to 10 minutes
* AJN-5) Changed maximum number of blocks to skip when
* reading tapes with multiple consecutive write
* errors from 100 to 1000 in idetape_get_logical_blk
* Proposed changes to code:
* 1) output "logical_blk_num" via /proc
* 2) output "current_operation" via /proc
* 3) Either solve or document the fact that `mt rewind' is
* required after reading from /dev/nhtx to be
* able to rmmod the idetape module;
* Also, sometimes an application finishes but the
* device remains `busy' for some time. Same cause ?
* Proposed changes to release-notes:
* 4) write a simple `quickstart' section in the
* release notes; I volunteer if you don't want to
* 5) include a pointer to video4linux in the doc
* to stimulate video applications
* 6) release notes lines 331 and 362: explain what happens
* if the application data rate is higher than 1100 KB/s;
* similar approach to lower-than-500 kB/s ?
* 7) 6.6 Comparison; wouldn't it be better to allow different
* strategies for read and write ?
* Wouldn't it be better to control the tape buffer
* contents instead of the bandwidth ?
* 8) line 536: replace will by would (if I understand
* this section correctly, a hypothetical and unwanted situation
* is being described)
* Ver 1.16f Dec 15 99 Change place of the secondary OnStream header frames.
* Ver 1.17 Nov 2000 / Jan 2001 Marcel Mol, marcel@mesa.nl
* - Add idetape_onstream_mode_sense_tape_parameter_page
* function to get tape capacity in frames: tape->capacity.
* - Add support for DI-50 drives( or any DI- drive).
* - 'workaround' for read error/blank block around block 3000.
* - Implement Early warning for end of media for Onstream.
* - Cosmetic code changes for readability.
* - Idetape_position_tape should not use SKIP bit during
* Onstream read recovery.
* - Add capacity, logical_blk_num and first/last_frame_position
* to /proc/ide/hd?/settings.
* - Module use count was gone in the Linux 2.4 driver.
* Ver 1.17a Apr 2001 Willem Riede osst@riede.org
* - Get drive's actual block size from mode sense block descriptor
* - Limit size of pipeline
* Ver 1.17b Oct 2002 Alan Stern <stern@rowland.harvard.edu>
* Changed IDETAPE_MIN_PIPELINE_STAGES to 1 and actually used
* it in the code!
* Actually removed aborted stages in idetape_abort_pipeline
* instead of just changing the command code.
* Made the transfer byte count for Request Sense equal to the
* actual length of the data transfer.
* Changed handling of partial data transfers: they do not
* cause DMA errors.
* Moved initiation of DMA transfers to the correct place.
* Removed reference to unallocated memory.
* Made __idetape_discard_read_pipeline return the number of
* sectors skipped, not the number of stages.
* Replaced errant kfree() calls with __idetape_kfree_stage().
* Fixed off-by-one error in testing the pipeline length.
* Fixed handling of filemarks in the read pipeline.
* Small code optimization for MTBSF and MTBSFM ioctls.
* Don't try to unlock the door during device close if is
* already unlocked!
* Cosmetic fixes to miscellaneous debugging output messages.
* Set the minimum /proc/ide/hd?/settings values for "pipeline",
* "pipeline_min", and "pipeline_max" to 1.
*/
|
