| .\" sd.4 |
| .\" Copyright 1992 Rickard E. Faith (faith@cs.unc.edu) |
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| .TH SD 4 2017-09-15 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| sd \- driver for SCSI disk drives |
| .SH SYNOPSIS |
| .nf |
| .BR "#include <linux/hdreg.h> " "/* for HDIO_GETGEO */" |
| .BR "#include <linux/fs.h> " "/* for BLKGETSIZE and BLKRRPART */" |
| .fi |
| .SH CONFIGURATION |
| The block device name has the following form: |
| .BI sd lp, |
| where |
| .I l |
| is a letter denoting the physical drive, and |
| .I p |
| is a number denoting the partition on that physical drive. |
| Often, the partition number, |
| .IR p , |
| will be left off when the device corresponds to the whole drive. |
| .PP |
| SCSI disks have a major device number of 8, and a minor device number of |
| the form (16 * |
| .IR drive_number ") + " partition_number , |
| where |
| .I drive_number |
| is the number of the physical drive in order of detection, and |
| .I partition_number |
| is as follows: |
| .IP +3 |
| partition 0 is the whole drive |
| .IP |
| partitions 1\(en4 are the DOS "primary" partitions |
| .IP |
| partitions 5\(en8 are the DOS "extended" (or "logical") partitions |
| .PP |
| For example, |
| .I /dev/sda |
| will have major 8, minor 0, and will refer to all of the first SCSI drive |
| in the system; and |
| .I /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. |
| .PP |
| At this time, only block devices are provided. |
| Raw devices have not yet been implemented. |
| .SH DESCRIPTION |
| The following |
| .IR ioctl s |
| are provided: |
| .TP |
| .B HDIO_GETGEO |
| Returns the BIOS disk parameters in the following structure: |
| .PP |
| .in +4n |
| .EX |
| struct hd_geometry { |
| unsigned char heads; |
| unsigned char sectors; |
| unsigned short cylinders; |
| unsigned long start; |
| }; |
| .EE |
| .in |
| .IP |
| A pointer to this structure is passed as the |
| .BR ioctl (2) |
| parameter. |
| .IP |
| The information returned in the parameter is the disk geometry of the drive |
| .I "as understood by DOS!" |
| This geometry is |
| .I 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 |
| .BR fdisk (1), |
| .BR efdisk (1), |
| and |
| .BR lilo (1). |
| If the geometry information is not available, zero will be returned for all |
| of the parameters. |
| .TP |
| .B BLKGETSIZE |
| Returns the device size in sectors. |
| The |
| .BR ioctl (2) |
| parameter should be a pointer to a |
| .IR long . |
| .TP |
| .B BLKRRPART |
| Forces a reread of the SCSI disk partition tables. |
| No parameter is needed. |
| .IP |
| The SCSI |
| .BR ioctl (2) |
| operations are also supported. |
| If the |
| .BR ioctl (2) |
| parameter is required, and it is NULL, then |
| .BR ioctl (2) |
| fails with the error |
| .BR EINVAL . |
| .SH FILES |
| .TP |
| .I /dev/sd[a\-h] |
| the whole device |
| .TP |
| .I /dev/sd[a\-h][0\-8] |
| individual block partitions |
| .\".SH SEE ALSO |
| .\".BR scsi (4) |