| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | The compile-time configurable defaults for the Linux SCSI tape driver. |
| 3 | |
| 4 | Copyright 1995 Kai Makisara. |
| 5 | |
| 6 | Last modified: Wed Sep 2 21:24:07 1998 by root@home |
| 7 | |
| 8 | Changed (and renamed) for OnStream SCSI drives garloff@suse.de |
| 9 | 2000-06-21 |
| 10 | |
| 11 | $Header: /cvsroot/osst/Driver/osst_options.h,v 1.6 2003/12/23 14:22:12 wriede Exp $ |
| 12 | */ |
| 13 | |
| 14 | #ifndef _OSST_OPTIONS_H |
| 15 | #define _OSST_OPTIONS_H |
| 16 | |
| 17 | /* The minimum limit for the number of SCSI tape devices is determined by |
| 18 | OSST_MAX_TAPES. If the number of tape devices and the "slack" defined by |
| 19 | OSST_EXTRA_DEVS exceeds OSST_MAX_TAPES, the large number is used. */ |
| 20 | #define OSST_MAX_TAPES 4 |
| 21 | |
| 22 | /* If OSST_IN_FILE_POS is nonzero, the driver positions the tape after the |
| 23 | record been read by the user program even if the tape has moved further |
| 24 | because of buffered reads. Should be set to zero to support also drives |
| 25 | that can't space backwards over records. NOTE: The tape will be |
| 26 | spaced backwards over an "accidentally" crossed filemark in any case. */ |
| 27 | #define OSST_IN_FILE_POS 1 |
| 28 | |
| 29 | /* The tape driver buffer size in kilobytes. */ |
| 30 | /* Don't change, as this is the HW blocksize */ |
| 31 | #define OSST_BUFFER_BLOCKS 32 |
| 32 | |
| 33 | /* The number of kilobytes of data in the buffer that triggers an |
| 34 | asynchronous write in fixed block mode. See also OSST_ASYNC_WRITES |
| 35 | below. */ |
| 36 | #define OSST_WRITE_THRESHOLD_BLOCKS 32 |
| 37 | |
| 38 | /* OSST_EOM_RESERVE defines the number of frames are kept in reserve for |
| 39 | * * write error recovery when writing near end of medium. ENOSPC is returned |
| 40 | * * when write() is called and the tape write position is within this number |
| 41 | * * of blocks from the tape capacity. */ |
| 42 | #define OSST_EOM_RESERVE 300 |
| 43 | |
| 44 | /* The maximum number of tape buffers the driver allocates. The number |
| 45 | is also constrained by the number of drives detected. Determines the |
| 46 | maximum number of concurrently active tape drives. */ |
| 47 | #define OSST_MAX_BUFFERS OSST_MAX_TAPES |
| 48 | |
| 49 | /* Maximum number of scatter/gather segments */ |
| 50 | /* Fit one buffer in pages and add one for the AUX header */ |
| 51 | #define OSST_MAX_SG (((OSST_BUFFER_BLOCKS*1024) / PAGE_SIZE) + 1) |
| 52 | |
| 53 | /* The number of scatter/gather segments to allocate at first try (must be |
| 54 | smaller or equal to the maximum). */ |
| 55 | #define OSST_FIRST_SG ((OSST_BUFFER_BLOCKS*1024) / PAGE_SIZE) |
| 56 | |
| 57 | /* The size of the first scatter/gather segments (determines the maximum block |
| 58 | size for SCSI adapters not supporting scatter/gather). The default is set |
| 59 | to try to allocate the buffer as one chunk. */ |
| 60 | #define OSST_FIRST_ORDER (15-PAGE_SHIFT) |
| 61 | |
| 62 | |
| 63 | /* The following lines define defaults for properties that can be set |
| 64 | separately for each drive using the MTSTOPTIONS ioctl. */ |
| 65 | |
| 66 | /* If OSST_TWO_FM is non-zero, the driver writes two filemarks after a |
| 67 | file being written. Some drives can't handle two filemarks at the |
| 68 | end of data. */ |
| 69 | #define OSST_TWO_FM 0 |
| 70 | |
| 71 | /* If OSST_BUFFER_WRITES is non-zero, writes in fixed block mode are |
| 72 | buffered until the driver buffer is full or asynchronous write is |
| 73 | triggered. */ |
| 74 | #define OSST_BUFFER_WRITES 1 |
| 75 | |
| 76 | /* If OSST_ASYNC_WRITES is non-zero, the SCSI write command may be started |
| 77 | without waiting for it to finish. May cause problems in multiple |
| 78 | tape backups. */ |
| 79 | #define OSST_ASYNC_WRITES 1 |
| 80 | |
| 81 | /* If OSST_READ_AHEAD is non-zero, blocks are read ahead in fixed block |
| 82 | mode. */ |
| 83 | #define OSST_READ_AHEAD 1 |
| 84 | |
| 85 | /* If OSST_AUTO_LOCK is non-zero, the drive door is locked at the first |
| 86 | read or write command after the device is opened. The door is opened |
| 87 | when the device is closed. */ |
| 88 | #define OSST_AUTO_LOCK 0 |
| 89 | |
| 90 | /* If OSST_FAST_MTEOM is non-zero, the MTEOM ioctl is done using the |
| 91 | direct SCSI command. The file number status is lost but this method |
| 92 | is fast with some drives. Otherwise MTEOM is done by spacing over |
| 93 | files and the file number status is retained. */ |
| 94 | #define OSST_FAST_MTEOM 0 |
| 95 | |
| 96 | /* If OSST_SCSI2LOGICAL is nonzero, the logical block addresses are used for |
| 97 | MTIOCPOS and MTSEEK by default. Vendor addresses are used if OSST_SCSI2LOGICAL |
| 98 | is zero. */ |
| 99 | #define OSST_SCSI2LOGICAL 0 |
| 100 | |
| 101 | /* If OSST_SYSV is non-zero, the tape behaves according to the SYS V semantics. |
| 102 | The default is BSD semantics. */ |
| 103 | #define OSST_SYSV 0 |
| 104 | |
| 105 | |
| 106 | #endif |