DISK(5)                 GENIX Programmer's Manual                 DISK(5)



      NAME
           disk - format of a disk header

      SYNOPSIS
           #include <sys/disk.h>

      DESCRIPTION
           Disk.h describes the header that must be present on all disk drives.
           The  GENIX disk driver reads this drive header and configures itself
           accordingly to accomodate the  drive.   This  allows  new  disks  of
           differing  capacities to be freely added with no changes required of
           the GENIX disk driver.

           The drive header is initially installed, and the drive configuration
           data  may be edited, by the dcutest(8) program.  Mkpt(8) may be used
           to edit the partition table information.

           #define DMAGIC 0x6d737000          /* The disk magic number */
           #ifndef BSIZE
           #define BSIZE  1024           /* the default block size */
           #endif

           /*
            *   The basic disk configuration data
            */

           struct dcon {
                short     dc_nsectors;   /* # of sectors per track */
                short     dc_ntracks;    /* # of tracks per cylinder */
                short     dc_ncylinders; /* # of cylinders per unit */
                short     dc_secpercyl;  /* # of sectors per cylinder */
                long dc_secperunit; /* # of sectors per unit */
           };

           /*
            *   The configuration data used by the disk drivers. This is a
            *   subset of the full configuration data stored on the disk, as
            *   the kernel driver doesn't need everything.
            */

           typedef struct {
                struct dcon dc;          /* the configuration data */
                struct partition {  /* the partition table */
                     int  nblocks;/* number of sectors in partition */
                     int  cyloff;   /* starting cylinder offset for partition */
                } dd_partition[8];
           } dcdata;

           #define d_nsectors       dc.dc_nsectors
           #define d_ntracks        dc.dc_ntracks
           #define d_ncylinders          dc.dc_ncylinders
           #define d_secpercyl      dc.dc_secpercyl



      Printed 11/16/83                                                        1

      DISK(5)                 GENIX Programmer's Manual                 DISK(5)



           #define d_secperunit          dc.dc_secperunit

           /*
            *   The full configuration data stored on block 0 of the disk
            */

           struct disktab {
                long dt_magic; /* the magic number */
                short     dt_ploz;  /* formatting data for sector zero */
                short     dt_plonz; /* formatting data for non-zero sectors */
                dcdata    dt_dd;         /* device driver data */
                char dt_name[8];    /* a buffer for the name of the disk */
           };

           #define dt_dc       dt_dd.dc
           #define dt_nsectors dt_dc.dc_nsectors
           #define dt_ntracks  dt_dc.dc_ntracks
           #define dt_ncylinders    dt_dc.dc_ncylinders
           #define dt_secpercyl     dt_dc.dc_secpercyl
           #define dt_secperunit    dt_dc.dc_secperunit
           #define dt_partition     dt_dd.dd_partition

           /*
            *   Default configurations used by stand alone driver for
            *   auto-configure feature. An array of these exists in
            *   dcusaio.c, one entry per known drive type.
            */

           struct unitdata {
                short     ud_ploz;  /* formatting data for sector zero */
                short     ud_plonz; /* formatting data for non-zero sectors */
                struct    dcon dc;  /* the configuration data */
                struct    partition *ud_pt;/* pointer to disk partition table*/
                char   *ud_name;    /* name of disk type */
           };

           /*
            *   A convenience for assigning partition tables
            */

           typedef struct {
                struct partition pt[8];
           } partitions;


      SEE ALSO
           dc(4), dcutest(8), mkpt(8)








      Printed 11/16/83                                                        2