hd

Purpose

     Supports the fixed-disk device driver.

Synopsis

     #include <sys/devinfo.h>

Description

     The fixed-disk device driver provides block and character
     (raw) access to minidisks  on the fixed-disk drives.  The
     config device  driver associates the minor  device number
     to the  minidisk.  Normally,  the special  files /dev/hdn
     and /dev/rhdn is given the minor device number n.

     The minidisk  with minor  device number  0 is  always the
     minidisk used to initially load the system program.

     In raw I/O , the buffer  must always begin on a full word
     boundary, and counts should be a multiple of 512 bytes (a
     disk block).  Likewise lseek  system calls should specify
     a multiple of 512 bytes.

     Configuration Data

     The config device driver  is called at its initialization
     entry  point during  system  initialization to  customize
     minidisks.  The following shows the structure of the cus-
     tomize information:

          struct {
             dev_t  devno;           /* major/minor device number */
             unsigned short iodn;    /* IODN set */
             unsigned short ddilen;  /* device dependent info length */
             short  lev;             /* ignored */
             union  {                /* optional device dependent info */
                struct {             /* for Send Command SVC */
                   int rv2,
                   rv3,
                   rv4,
                   rv5,
                   rv6;
                   } ddi_sc;
                  . . .                    /* ddi for other devices */
             } ddi;
           };

     If  the  iodn   field  is  0,  the   manager  receives  a
     Send_Command supervisor call (SVC)  with values rv2, rv3,
     rv4, rv5  and rv6 in  registers 2, 3,  4, 5, and  6.  The
     driver waits  for the manager  to return a  completion or

     error  interrupt.  The  return value  is the  status code
     returned at the interrupt, which can be obtained using an
     ioctl system call to the config device driver.

     ioctl Operations

     The VQUERY type ioctl  call queries the disk write-verify
     status for the minidisk.  It uses the form:

           ioctl (fildes, command, arg)
           struct wverify *arg

     where arg is a pointer  to the one-word structure wverify
     that contains the write verify  status to be returned.  A
     value of 1 returned indicates enabled and 0 if disabled.

     The  VCNTRL type  ioctl  call enables  or disables  write
     verify for the minidisk.  It uses the form:

           ioctl (fildes, command, arg)
           int arg;

     where an  arg value of 0  is used to disable  disk write-
     verify and  a value of  1 is  used to enable  disk write-
     verify.

     See  "mdverify" for  another  way to  set  and query  the
     write-verify status of a minidisk.

     The IOCTYPE  type ioctl  call returns the  value DD_DISK,
     defined in <sys/devinfo.h>.

     The IOCINFO type ioctl  call returns the following struc-
     ture, defined in <sys/devinfo.h>:

           struct devinfo {
              char devtype;
              char flags;
              union {
                 struct {        /* for disks */
                 short bytpsec;  /* bytes per sector */
                 short secptrk;  /* sectors per track */
                 short trkpcyl;  /* tracks per cylinder */
                 long numblks;   /* blocks this mini-disk */
                } dk;
                   . . .                      /* for other devices */
             } un;
           };

          /*flags */
          #define DF_FIXED 01  /* non-removable */
          #define DF_RAND  02  /* random access possible */
          #define DF_FAST  04  /* a relative term */

Files

     /dev/hd0, /dev/hd1, . . .
     /dev/rhd0, /dev/rhd1, . . .

Related Information

     In this book:  "config,"  "fs," "ioctl," and  "lseek."