usr/src/sys/dev/cdvar.h

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * %sccs.include.redist.c%
 *
 * from: Utah $Hdr: cdvar.h 1.4 89/09/17$
 *
 *      @(#)cdvar.h     7.1 (Berkeley) %G%
 */

#define NCDISKS 8                       /* max # of component disks */

/*
 * A concatenated disk is described at config time by this structure.
 */
struct cddevice {
        int     cd_unit;                /* logical unit of this cd */
        int     cd_interleave;          /* interleave (DEV_BSIZE blocks) */
        int     cd_flags;               /* misc. information */
        int     cd_dk;                  /* disk number */
        dev_t   cd_dev[NCDISKS];        /* component devices */
};

/* cd_flags */
#define CDF_SWAP        0x01    /* interleave should be dmmax */
#define CDF_UNIFORM     0x02    /* use LCD of sizes for uniform interleave */

/*
 * Component info table.
 * Describes a single component of a concatenated disk.
 */
struct cdcinfo {
        dev_t           ci_dev;  /* devno */
        size_t          ci_size; /* size */
};

/*
 * Interleave description table.
 * Computed at boot time to speed irregular-interleave lookups.
 * The idea is that we interleave in "groups".  First we interleave
 * evenly over all component disks up to the size of the smallest
 * component (the first group), then we interleave evenly over all
 * remaining disks up to the size of the next-smallest (second group),
 * and so on.
 *
 * Each table entry describes the interleave characteristics of one
 * of these groups.  For example if a concatenated disk consisted of
 * three components of 5, 3, and 7 DEV_BSIZE blocks interleaved at
 * DEV_BSIZE (1), the table would have three entries:
 *
 *      ndisk   startblk        startoff        dev
 *      3       0               0               0, 1, 2
 *      2       9               3               0, 2
 *      1       13              5               2
 *      0       -               -               -
 *
 * which says that the first nine blocks (0-8) are interleaved over
 * 3 disks (0, 1, 2) starting at block offset 0 on any component disk,
 * the next 4 blocks (9-12) are interleaved over 2 disks (0, 2) starting
 * at component block 3, and the remaining blocks (13-14) are on disk
 * 2 starting at offset 5.
 */
struct cdiinfo {
        int     ii_ndisk;       /* # of disks range is interleaved over */
        daddr_t ii_startblk;    /* starting scaled block # for range */
        daddr_t ii_startoff;    /* starting component offset (block #) */
        char    ii_index[NCDISKS];/* ordered list of components in range */
};

#ifdef KERNEL
extern  struct cddevice cddevice[];
#endif