108 lines
4.1 KiB
C
108 lines
4.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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The compile-time configurable defaults for the Linux SCSI tape driver.
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Copyright 1995 Kai Makisara.
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Last modified: Wed Sep 2 21:24:07 1998 by root@home
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Changed (and renamed) for OnStream SCSI drives garloff@suse.de
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2000-06-21
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$Header: /cvsroot/osst/Driver/osst_options.h,v 1.6 2003/12/23 14:22:12 wriede Exp $
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*/
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#ifndef _OSST_OPTIONS_H
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#define _OSST_OPTIONS_H
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/* The minimum limit for the number of SCSI tape devices is determined by
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OSST_MAX_TAPES. If the number of tape devices and the "slack" defined by
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OSST_EXTRA_DEVS exceeds OSST_MAX_TAPES, the large number is used. */
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#define OSST_MAX_TAPES 4
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/* If OSST_IN_FILE_POS is nonzero, the driver positions the tape after the
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record been read by the user program even if the tape has moved further
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because of buffered reads. Should be set to zero to support also drives
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that can't space backwards over records. NOTE: The tape will be
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spaced backwards over an "accidentally" crossed filemark in any case. */
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#define OSST_IN_FILE_POS 1
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/* The tape driver buffer size in kilobytes. */
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/* Don't change, as this is the HW blocksize */
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#define OSST_BUFFER_BLOCKS 32
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/* The number of kilobytes of data in the buffer that triggers an
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asynchronous write in fixed block mode. See also OSST_ASYNC_WRITES
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below. */
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#define OSST_WRITE_THRESHOLD_BLOCKS 32
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/* OSST_EOM_RESERVE defines the number of frames are kept in reserve for
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* * write error recovery when writing near end of medium. ENOSPC is returned
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* * when write() is called and the tape write position is within this number
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* * of blocks from the tape capacity. */
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#define OSST_EOM_RESERVE 300
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/* The maximum number of tape buffers the driver allocates. The number
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is also constrained by the number of drives detected. Determines the
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maximum number of concurrently active tape drives. */
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#define OSST_MAX_BUFFERS OSST_MAX_TAPES
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/* Maximum number of scatter/gather segments */
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/* Fit one buffer in pages and add one for the AUX header */
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#define OSST_MAX_SG (((OSST_BUFFER_BLOCKS*1024) / PAGE_SIZE) + 1)
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/* The number of scatter/gather segments to allocate at first try (must be
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smaller or equal to the maximum). */
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#define OSST_FIRST_SG ((OSST_BUFFER_BLOCKS*1024) / PAGE_SIZE)
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/* The size of the first scatter/gather segments (determines the maximum block
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size for SCSI adapters not supporting scatter/gather). The default is set
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to try to allocate the buffer as one chunk. */
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#define OSST_FIRST_ORDER (15-PAGE_SHIFT)
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/* The following lines define defaults for properties that can be set
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separately for each drive using the MTSTOPTIONS ioctl. */
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/* If OSST_TWO_FM is non-zero, the driver writes two filemarks after a
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file being written. Some drives can't handle two filemarks at the
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end of data. */
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#define OSST_TWO_FM 0
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/* If OSST_BUFFER_WRITES is non-zero, writes in fixed block mode are
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buffered until the driver buffer is full or asynchronous write is
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triggered. */
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#define OSST_BUFFER_WRITES 1
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/* If OSST_ASYNC_WRITES is non-zero, the SCSI write command may be started
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without waiting for it to finish. May cause problems in multiple
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tape backups. */
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#define OSST_ASYNC_WRITES 1
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/* If OSST_READ_AHEAD is non-zero, blocks are read ahead in fixed block
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mode. */
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#define OSST_READ_AHEAD 1
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/* If OSST_AUTO_LOCK is non-zero, the drive door is locked at the first
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read or write command after the device is opened. The door is opened
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when the device is closed. */
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#define OSST_AUTO_LOCK 0
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/* If OSST_FAST_MTEOM is non-zero, the MTEOM ioctl is done using the
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direct SCSI command. The file number status is lost but this method
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is fast with some drives. Otherwise MTEOM is done by spacing over
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files and the file number status is retained. */
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#define OSST_FAST_MTEOM 0
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/* If OSST_SCSI2LOGICAL is nonzero, the logical block addresses are used for
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MTIOCPOS and MTSEEK by default. Vendor addresses are used if OSST_SCSI2LOGICAL
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is zero. */
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#define OSST_SCSI2LOGICAL 0
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/* If OSST_SYSV is non-zero, the tape behaves according to the SYS V semantics.
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The default is BSD semantics. */
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#define OSST_SYSV 0
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#endif
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