hdio.txt

linux 内核源代码

		Summary of HDIO_ ioctl calls.
		============================

		Edward A. Falk <[e-mail]>

		November, 2004

This document attempts to describe the ioctl(2) calls supported by
the HD/IDE layer.  These are by-and-large implemented (as of Linux 2.6)
in drivers/ide/ide.c and drivers/block/scsi_ioctl.c

ioctl values are listed in <linux/hdreg.h>.  As of this writing, they
are as follows:

    ioctls that pass argument pointers to user space:

	HDIO_GETGEO		get device geometry
	HDIO_GET_UNMASKINTR	get current unmask setting
	HDIO_GET_MULTCOUNT	get current IDE blockmode setting
	HDIO_GET_QDMA		get use-qdma flag
	HDIO_SET_XFER		set transfer rate via proc
	HDIO_OBSOLETE_IDENTITY	OBSOLETE, DO NOT USE
	HDIO_GET_KEEPSETTINGS	get keep-settings-on-reset flag
	HDIO_GET_32BIT		get current io_32bit setting
	HDIO_GET_NOWERR		get ignore-write-error flag
	HDIO_GET_DMA		get use-dma flag
	HDIO_GET_NICE		get nice flags
	HDIO_GET_IDENTITY	get IDE identification info
	HDIO_GET_WCACHE		get write cache mode on|off
	HDIO_GET_ACOUSTIC	get acoustic value
	HDIO_GET_ADDRESS	get sector addressing mode
	HDIO_GET_BUSSTATE	get the bus state of the hwif
	HDIO_TRISTATE_HWIF	execute a channel tristate
	HDIO_DRIVE_RESET	execute a device reset
	HDIO_DRIVE_TASKFILE	execute raw taskfile
	HDIO_DRIVE_TASK		execute task and special drive command
	HDIO_DRIVE_CMD		execute a special drive command
	HDIO_DRIVE_CMD_AEB	HDIO_DRIVE_TASK

    ioctls that pass non-pointer values:

	HDIO_SET_MULTCOUNT	change IDE blockmode
	HDIO_SET_UNMASKINTR	permit other irqs during I/O
	HDIO_SET_KEEPSETTINGS	keep ioctl settings on reset
	HDIO_SET_32BIT		change io_32bit flags
	HDIO_SET_NOWERR		change ignore-write-error flag
	HDIO_SET_DMA		change use-dma flag
	HDIO_SET_PIO_MODE	reconfig interface to new speed
	HDIO_SCAN_HWIF		register and (re)scan interface
	HDIO_SET_NICE		set nice flags
	HDIO_UNREGISTER_HWIF	unregister interface
	HDIO_SET_WCACHE		change write cache enable-disable
	HDIO_SET_ACOUSTIC	change acoustic behavior
	HDIO_SET_BUSSTATE	set the bus state of the hwif
	HDIO_SET_QDMA		change use-qdma flag
	HDIO_SET_ADDRESS	change lba addressing modes

	HDIO_SET_IDE_SCSI	Set scsi emulation mode on/off
	HDIO_SET_SCSI_IDE	not implemented yet


The information that follows was determined from reading kernel source
code.  It is likely that some corrections will be made over time.







General:

	Unless otherwise specified, all ioctl calls return 0 on success
	and -1 with errno set to an appropriate value on error.

	Unless otherwise specified, all ioctl calls return -1 and set
	errno to EFAULT on a failed attempt to copy data to or from user
	address space.

	Unless otherwise specified, all data structures and constants
	are defined in <linux/hdreg.h>



HDIO_GETGEO			get device geometry

	usage:

	  struct hd_geometry geom;
	  ioctl(fd, HDIO_GETGEO, &geom);


	inputs:		none

	outputs:

	  hd_geometry structure containing:

	    heads	number of heads
	    sectors	number of sectors/track
	    cylinders	number of cylinders, mod 65536
	    start	starting sector of this partition.


	error returns:
	  EINVAL	if the device is not a disk drive or floppy drive,
	  		or if the user passes a null pointer


	notes:

	  Not particularly useful with modern disk drives, whose geometry
	  is a polite fiction anyway.  Modern drives are addressed
	  purely by sector number nowadays (lba addressing), and the
	  drive geometry is an abstraction which is actually subject
	  to change.  Currently (as of Nov 2004), the geometry values
	  are the "bios" values -- presumably the values the drive had
	  when Linux first booted.

	  In addition, the cylinders field of the hd_geometry is an
	  unsigned short, meaning that on most architectures, this
	  ioctl will not return a meaningful value on drives with more
	  than 65535 tracks.

	  The start field is unsigned long, meaning that it will not
	  contain a meaningful value for disks over 219 Gb in size.




HDIO_GET_UNMASKINTR		get current unmask setting

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_UNMASKINTR, &val);

	inputs:		none

	outputs:
	  The value of the drive's current unmask setting



HDIO_SET_UNMASKINTR		permit other irqs during I/O

	usage:

	  unsigned long val;
	  ioctl(fd, HDIO_SET_UNMASKINTR, val);

	inputs:
	  New value for unmask flag

	outputs:	none

	error return:
	  EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  EACCES	Access denied:  requires CAP_SYS_ADMIN
	  EINVAL	value out of range [0 1]
	  EBUSY		Controller busy




HDIO_GET_MULTCOUNT		get current IDE blockmode setting

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_MULTCOUNT, &val);

	inputs:		none

	outputs:
	  The value of the current IDE block mode setting.  This
	  controls how many sectors the drive will transfer per
	  interrupt.



HDIO_SET_MULTCOUNT		change IDE blockmode

	usage:

	  int val;
	  ioctl(fd, HDIO_SET_MULTCOUNT, val);

	inputs:
	  New value for IDE block mode setting.  This controls how many
	  sectors the drive will transfer per interrupt.

	outputs:	none

	error return:
	  EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  EACCES	Access denied:  requires CAP_SYS_ADMIN
	  EINVAL	value out of range supported by disk.
	  EBUSY		Controller busy or blockmode already set.
	  EIO		Drive did not accept new block mode.

	notes:

	  Source code comments read:

	    This is tightly woven into the driver->do_special cannot
	    touch.  DON'T do it again until a total personality rewrite
	    is committed.

	  If blockmode has already been set, this ioctl will fail with
	  EBUSY



HDIO_GET_QDMA			get use-qdma flag

	Not implemented, as of 2.6.8.1



HDIO_SET_XFER			set transfer rate via proc

	Not implemented, as of 2.6.8.1



HDIO_OBSOLETE_IDENTITY		OBSOLETE, DO NOT USE

	Same as HDIO_GET_IDENTITY (see below), except that it only
	returns the first 142 bytes of drive identity information.



HDIO_GET_IDENTITY		get IDE identification info

	usage:

	  unsigned char identity[512];
	  ioctl(fd, HDIO_GET_IDENTITY, identity);

	inputs:		none

	outputs:

	  ATA drive identity information.  For full description, see
	  the IDENTIFY DEVICE and IDENTIFY PACKET DEVICE commands in
	  the ATA specification.

	error returns:
	  EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  ENOMSG	IDENTIFY DEVICE information not available

	notes:

	  Returns information that was obtained when the drive was
	  probed.  Some of this information is subject to change, and
	  this ioctl does not re-probe the drive to update the
	  information.

	  This information is also available from /proc/ide/hdX/identify



HDIO_GET_KEEPSETTINGS		get keep-settings-on-reset flag

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_KEEPSETTINGS, &val);

	inputs:		none

	outputs:
	  The value of the current "keep settings" flag

	notes:

	  When set, indicates that kernel should restore settings
	  after a drive reset.



HDIO_SET_KEEPSETTINGS		keep ioctl settings on reset

	usage:

	  long val;
	  ioctl(fd, HDIO_SET_KEEPSETTINGS, val);

	inputs:
	  New value for keep_settings flag

	outputs:	none

	error return:
	  EINVAL	(bdev != bdev->bd_contains) (not sure what this means)
	  EACCES	Access denied:  requires CAP_SYS_ADMIN
	  EINVAL	value out of range [0 1]
	  EBUSY		Controller busy



HDIO_GET_32BIT			get current io_32bit setting

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_32BIT, &val);

	inputs:		none

	outputs:
	  The value of the current io_32bit setting

	notes:

	  0=16-bit, 1=32-bit, 2,3 = 32bit+sync



HDIO_GET_NOWERR			get ignore-write-error flag

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_NOWERR, &val);

	inputs:		none

	outputs:
	  The value of the current ignore-write-error flag



HDIO_GET_DMA			get use-dma flag

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_DMA, &val);

	inputs:		none

	outputs:
	  The value of the current use-dma flag



HDIO_GET_NICE			get nice flags

	usage:

	  long nice;
	  ioctl(fd, HDIO_GET_NICE, &nice);

	inputs:		none

	outputs:

	  The drive's "nice" values.

	notes:

	  Per-drive flags which determine when the system will give more
	  bandwidth to other devices sharing the same IDE bus.
	  See <linux/hdreg.h>, near symbol IDE_NICE_DSC_OVERLAP.




HDIO_SET_NICE			set nice flags

	usage:

	  unsigned long nice;
	  ...
	  ioctl(fd, HDIO_SET_NICE, nice);

	inputs:
	  bitmask of nice flags.

	outputs:	none

	error returns:
	  EACCES	Access denied:  requires CAP_SYS_ADMIN
	  EPERM		Flags other than DSC_OVERLAP and NICE_1 set.
	  EPERM		DSC_OVERLAP specified but not supported by drive

	notes:

	  This ioctl sets the DSC_OVERLAP and NICE_1 flags from values
	  provided by the user.

	  Nice flags are listed in <linux/hdreg.h>, starting with
	  IDE_NICE_DSC_OVERLAP.  These values represent shifts.





HDIO_GET_WCACHE			get write cache mode on|off

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_WCACHE, &val);

	inputs:		none

	outputs:
	  The value of the current write cache mode



HDIO_GET_ACOUSTIC		get acoustic value

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_ACOUSTIC, &val);

	inputs:		none

	outputs:
	  The value of the current acoustic settings

	notes:

	  See HDIO_SET_ACOUSTIC



HDIO_GET_ADDRESS

	usage:

	  long val;
	  ioctl(fd, HDIO_GET_ADDRESS, &val);

	inputs:		none

	outputs:
	  The value of the current addressing mode:
	    0 = 28-bit
	    1 = 48-bit
	    2 = 48-bit doing 28-bit
	    3 = 64-bit



HDIO_GET_BUSSTATE		get the bus state of the hwif

	usage:

	  long state;
	  ioctl(fd, HDIO_SCAN_HWIF, &state);

	inputs:		none

	outputs:
	  Current power state of the IDE bus.  One of BUSSTATE_OFF,
	  BUSSTATE_ON, or BUSSTATE_TRISTATE

	error returns:
	  EACCES	Access denied:  requires CAP_SYS_ADMIN




HDIO_SET_BUSSTATE		set the bus state of the hwif

	usage:

	  int state;
	  ...
	  ioctl(fd, HDIO_SCAN_HWIF, state);

	inputs:
	  Desired IDE power state.  One of BUSSTATE_OFF, BUSSTATE_ON,
	  or BUSSTATE_TRISTATE

	outputs:	none

	error returns:
	  EACCES	Access denied:  requires CAP_SYS_RAWIO
	  EOPNOTSUPP	Hardware interface does not support bus power control




HDIO_TRISTATE_HWIF		execute a channel tristate

	Not implemented, as of 2.6.8.1.  See HDIO_SET_BUSSTATE



HDIO_DRIVE_RESET		execute a device reset

	usage:

	  int args[3]
	  ...
	  ioctl(fd, HDIO_DRIVE_RESET, args);

	inputs:		none

	outputs:	none

	error returns:
	  EACCES	Access denied:  requires CAP_SYS_ADMIN

	notes:

	  Abort any current command, prevent anything else from being
	  queued, execute a reset on the device, and issue BLKRRPART
	  ioctl on the block device.

	  Executes an ATAPI soft reset if applicable, otherwise
	  executes an ATA soft reset on the controller.



HDIO_DRIVE_TASKFILE		execute raw taskfile

	Note:  If you don't have a copy of the ANSI ATA specification
	handy, you should probably ignore this ioctl.

	Execute an ATA disk command directly by writing the "taskfile"
	registers of the drive.  Requires ADMIN and RAWIO access
	privileges.

	usage:

	  struct {
	    ide_task_request_t req_task;
	    u8 outbuf[OUTPUT_SIZE];