ChangeLog.ide-tape.1995-2002 16 KB

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