SD

NAME

SYNOPSIS

#include <linux/hdreg.h>        /* for HDIO_GETGEO */
#include <linux/fs.h>           /* for BLKGETSIZE and BLKRRPART */

CONFIGURATION

SCSI disks have a major device number of 8, and a minor device number of the form (16 * drive_number) + partition_number, where drive_number is the number of the physical drive in order of detection, and partition_number is as follows:

partition 0 is the whole drive
partitions 1-4 are the DOS "primary" partitions
partitions 5-8 are the DOS "extended" (or "logical") partitions

For example, /dev/sda will have major 8, minor 0, and will refer to all of the first SCSI drive in the system; and /dev/sdb3 will have major 8, minor 19, and will refer to the third DOS "primary" partition on the second SCSI drive in the system.

At this time, only block devices are provided. Raw devices have not yet been implemented.  

DESCRIPTION

HDIO_GETGEO

Returns the BIOS disk parameters in the following structure:

struct hd_geometry {
    unsigned char  heads;
    unsigned char  sectors;
    unsigned short cylinders;
    unsigned long  start;
};

A pointer to this structure is passed as the ioctl(2) parameter.

The information returned in the parameter is the disk geometry of the drive as understood by DOS! This geometry is not the physical geometry of the drive. It is used when constructing the drive's partition table, however, and is needed for convenient operation of fdisk(1), efdisk(1), and lilo(1). If the geometry information is not available, zero will be returned for all of the parameters.

BLKGETSIZE

Returns the device size in sectors. The ioctl(2) parameter should be a pointer to a long.

BLKRRPART

Forces a re-read of the SCSI disk partition tables. No parameter is needed.

The scsi(4) ioctl(2) operations are also supported. If the ioctl(2) parameter is required, and it is NULL, then ioctl(2) will fail with the error EINVAL.

FILES

COLOPHON