drivers/scsi/st_options.h

   1 /*
   2    The compile-time configurable defaults for the Linux SCSI tape driver.
   3
   4    Copyright 1995-2003 Kai Makisara.
   5
   6    Last modified: Mon Apr  7 22:49:18 2003 by makisara
   7 */
   8
   9 #ifndef _ST_OPTIONS_H
  10 #define _ST_OPTIONS_H
  11
  12 /* If TRY_DIRECT_IO is non-zero, the driver tries to transfer data directly
  13    between the user buffer and tape drive. If this is not possible, driver
  14    buffer is used. If TRY_DIRECT_IO is zero, driver buffer is always used. */
  15 #define TRY_DIRECT_IO 1
  16
  17 /* The driver does not wait for some operations to finish before returning
  18    to the user program if ST_NOWAIT is non-zero. This helps if the SCSI
  19    adapter does not support multiple outstanding commands. However, the user
  20    should not give a new tape command before the previous one has finished. */
  21 #define ST_NOWAIT 0
  22
  23 /* If ST_IN_FILE_POS is nonzero, the driver positions the tape after the
  24    record been read by the user program even if the tape has moved further
  25    because of buffered reads. Should be set to zero to support also drives
  26    that can't space backwards over records. NOTE: The tape will be
  27    spaced backwards over an "accidentally" crossed filemark in any case. */
  28 #define ST_IN_FILE_POS 0
  29
  30 /* If ST_RECOVERED_WRITE_FATAL is non-zero, recovered errors while writing
  31    are considered "hard errors". */
  32 #define ST_RECOVERED_WRITE_FATAL 0
  33
  34 /* The "guess" for the block size for devices that don't support MODE
  35    SENSE. */
  36 #define ST_DEFAULT_BLOCK 0
  37
  38 /* The minimum tape driver buffer size in kilobytes in fixed block mode.
  39    Must be non-zero. */
  40 #define ST_FIXED_BUFFER_BLOCKS 32
  41
  42 /* Maximum number of scatter/gather segments */
  43 #define ST_MAX_SG      256
  44
  45 /* The number of scatter/gather segments to allocate at first try (must be
  46    smaller or equal to the maximum). */
  47 #define ST_FIRST_SG    8
  48
  49 /* The size of the first scatter/gather segments (determines the maximum block
  50    size for SCSI adapters not supporting scatter/gather). The default is set
  51    to try to allocate the buffer as one chunk. */
  52 #define ST_FIRST_ORDER  5
  53
  54
  55 /* The following lines define defaults for properties that can be set
  56    separately for each drive using the MTSTOPTIONS ioctl. */
  57
  58 /* If ST_TWO_FM is non-zero, the driver writes two filemarks after a
  59    file being written. Some drives can't handle two filemarks at the
  60    end of data. */
  61 #define ST_TWO_FM 0
  62
  63 /* If ST_BUFFER_WRITES is non-zero, writes in fixed block mode are
  64    buffered until the driver buffer is full or asynchronous write is
  65    triggered. May make detection of End-Of-Medium early enough fail. */
  66 #define ST_BUFFER_WRITES 1
  67
  68 /* If ST_ASYNC_WRITES is non-zero, the SCSI write command may be started
  69    without waiting for it to finish. May cause problems in multiple
  70    tape backups. */
  71 #define ST_ASYNC_WRITES 1
  72
  73 /* If ST_READ_AHEAD is non-zero, blocks are read ahead in fixed block
  74    mode. */
  75 #define ST_READ_AHEAD 1
  76
  77 /* If ST_AUTO_LOCK is non-zero, the drive door is locked at the first
  78    read or write command after the device is opened. The door is opened
  79    when the device is closed. */
  80 #define ST_AUTO_LOCK 0
  81
  82 /* If ST_FAST_MTEOM is non-zero, the MTEOM ioctl is done using the
  83    direct SCSI command. The file number status is lost but this method
  84    is fast with some drives. Otherwise MTEOM is done by spacing over
  85    files and the file number status is retained. */
  86 #define ST_FAST_MTEOM 0
  87
  88 /* If ST_SCSI2LOGICAL is nonzero, the logical block addresses are used for
  89    MTIOCPOS and MTSEEK by default. Vendor addresses are used if ST_SCSI2LOGICAL
  90    is zero. */
  91 #define ST_SCSI2LOGICAL 0
  92
  93 /* If ST_SYSV is non-zero, the tape behaves according to the SYS V semantics.
  94    The default is BSD semantics. */
  95 #define ST_SYSV 0
  96
  97 /* Time to wait for the drive to become ready if blocking open */
  98 #define ST_BLOCK_SECONDS     120
  99
 100 #endif