Summary of HDIO_ ioctl calls.
============================
Edward A. Falk <efalk@google.com>
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 can not
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];
u8 inbuf[INPUT_SIZE];
} task;
memset(&task.req_task, 0, sizeof(task.req_task));
task.req_task.out_size = sizeof(task.outbuf);
task.req_task.in_size = sizeof(task.inbuf);
...
ioctl(fd, HDIO_DRIVE_TASKFILE, &task);
...
inputs:
(See below for details on memory area passed to ioctl.)
io_ports[8] values to be written to taskfile registers
hob_ports[8] high-order bytes, for extended commands.
out_flags flags indicating which registers are valid
in_flags flags indicating which registers should be returned
data_phase see below
req_cmd command type to be executed
out_size size of output buffer
outbuf buffer of data to be transmitted to disk
inbuf buffer of data to be received from disk (see [1])
outputs:
io_ports[] values returned in the taskfile registers
hob_ports[] high-order bytes, for extended commands.
out_flags flags indicating which registers are valid (see [2])
in_flags flags indicating which registers should be returned
outbuf buffer of data to be transmitted to disk (see [1])
inbuf buffer of data to be received from disk
error returns:
EACCES CAP_SYS_ADMIN or CAP_SYS_RAWIO privilege not set.
ENOMSG Device is not a disk drive.
ENOMEM Unable to allocate memory for task
EFAULT req_cmd == TASKFILE_IN_OUT (not implemented as of 2.6.8)
EPERM req_cmd == TASKFILE_MULTI_OUT and drive
multi-count not yet set.
notes:
[1] Currently (2.6.8), both the input and output buffers are
copied from the user and written back to the user, even when
not used. This may be a bug.
[2] The out_flags and in_flags are returned to the user after
the ioctl completes. Currently (2.6.8) these are the same
as the input values, unchanged. In the future, they may have
more significance.
Extreme caution should be used with using this ioctl. A
mistake can easily corrupt data or hang the system.
The argument to the ioctl is a pointer to a region of memory
containing a ide_task_request_t structure, followed by an
optional buffer of data to be transmitted to the drive,
followed by an optional buffer to receive data from the drive.
Command is passed to the disk drive via the ide_task_request_t
structure, which contains these fields:
io_ports[8] values for the taskfile registers
hob_ports[8] high-order bytes, for extended commands
out_flags flags indicating which entries in the
io_ports[] and hob_ports[] arrays
contain valid values. Type ide_reg_valid_t.
in_flags flags indicating which entries in the
io_ports[] and hob_ports[] arrays
are expected to contain valid values
on return.
data_phase See below
req_cmd Command type, see below
out_size output (user->drive) buffer size, bytes
in_size input (drive->user) buffer size, bytes
This ioctl does not necessarily respect all flags in the
out_flags and in_flags values -- some taskfile registers
may be written or read even if not requested in the flags.
Unused fields of io_ports[] and hob_ports[] should be set
to zero.
The data_phase field describes the data transfer to be
performed. Value is one of:
TASKFILE_IN
TASKFILE_MULTI_IN
TASKFILE_OUT
TASKFILE_MULTI_OUT
TASKFILE_IN_OUT
TASKFILE_IN_DMA
TASKFILE_IN_DMAQ
TASKFILE_OUT_DMA
TASKFILE_OUT_DMAQ
TASKFILE_P_IN
TASKFILE_P_IN_DMA
TASKFILE_P_IN_DMAQ
TASKFILE_P_OUT
TASKFILE_P_OUT_DMA
TASKFILE_P_OUT_DMAQ
The req_cmd field classifies the command type. It may be
one of:
IDE_DRIVE_TASK_NO_DATA
IDE_DRIVE_TASK_SET_XFER
IDE_DRIVE_TASK_IN
IDE_DRIVE_TASK_OUT
IDE_DRIVE_TASK_RAW_WRITE
HDIO_DRIVE_CMD execute a special drive command
Note: If you don't have a copy of the ANSI ATA specification
handy, you should probably ignore this ioctl.
usage:
u8 args[4+XFER_SIZE];
...
ioctl(fd, HDIO_DRIVE_CMD, args);
inputs:
Taskfile register values:
args[0] COMMAND
args[1] SECTOR
args[2] FEATURE
args[3] NSECTOR
outputs:
args[] buffer is filled with register values followed by any
data returned by the disk.
args[0] status
args[1] error
args[2] NSECTOR
args[3] undefined
args[4+] NSECTOR * 512 bytes of data returned by the command.
error returns:
EACCES Access denied: requires CAP_SYS_RAWIO
ENOMEM Unable to allocate memory for task
notes:
Taskfile registers IDE_LCYL, IDE_HCYL, and IDE_SELECT are
set to zero before executing the command.
HDIO_DRIVE_TASK execute task and special drive command
Note: If you don't have a copy of the ANSI ATA specification
handy, you should probably ignore this ioctl.
usage:
u8 args[7];
...
ioctl(fd, HDIO_DRIVE_TASK, args);
inputs:
Taskfile register values:
args[0] COMMAND
args[1] FEATURE
args[2] NSECTOR
args[3] SECTOR
args[4] LCYL
args[5] HCYL
args[6] SELECT
outputs:
Taskfile register values:
args[0] status
args[1] error
args[2] NSECTOR
args[3] SECTOR
args[4] LCYL
args[5] HCYL
args[6] SELECT
error returns:
EACCES Access denied: requires CAP_SYS_RAWIO
ENOMEM Unable to allocate memory for task
HDIO_DRIVE_CMD_AEB HDIO_DRIVE_TASK
Not implemented, as of 2.6.8.1
HDIO_SET_32BIT change io_32bit flags
usage:
int val;
ioctl(fd, HDIO_SET_32BIT, val);
inputs:
New value for io_32bit 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 3]
EBUSY Controller busy
HDIO_SET_NOWERR change ignore-write-error flag
usage:
int val;
ioctl(fd, HDIO_SET_NOWERR, val);
inputs:
New value for ignore-write-error flag. Used for ignoring
WRERR_STAT
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_SET_DMA change use-dma flag
usage:
long val;
ioctl(fd, HDIO_SET_DMA, val);
inputs:
New value for use-dma 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_SET_PIO_MODE reconfig interface to new speed
usage:
long val;
ioctl(fd, HDIO_SET_PIO_MODE, val);
inputs:
New interface speed.
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 [0 255]
EBUSY Controller busy
HDIO_SCAN_HWIF register and (re)scan interface
usage:
int args[3]
...
ioctl(fd, HDIO_SCAN_HWIF, args);
inputs:
args[0] io address to probe
args[1] control address to probe
args[2] irq number
outputs: none
error returns:
EACCES Access denied: requires CAP_SYS_RAWIO
EIO Probe failed.
notes:
This ioctl initializes the addresses and irq for a disk
controller, probes for drives, and creates /proc/ide
interfaces as appropiate.
HDIO_UNREGISTER_HWIF unregister interface
usage:
int index;
ioctl(fd, HDIO_UNREGISTER_HWIF, index);
inputs:
index index of hardware interface to unregister
outputs: none
error returns:
EACCES Access denied: requires CAP_SYS_RAWIO
notes:
This ioctl removes a hardware interface from the kernel.
Currently (2.6.8) this ioctl silently fails if any drive on
the interface is busy.
HDIO_SET_WCACHE change write cache enable-disable
usage:
int val;
ioctl(fd, HDIO_SET_WCACHE, val);
inputs:
New value for write cache enable
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_SET_ACOUSTIC change acoustic behavior
usage:
int val;
ioctl(fd, HDIO_SET_ACOUSTIC, val);
inputs:
New value for drive acoustic settings
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 [0 254]
EBUSY Controller busy
HDIO_SET_QDMA change use-qdma flag
Not implemented, as of 2.6.8.1
HDIO_SET_ADDRESS change lba addressing modes
usage:
int val;
ioctl(fd, HDIO_SET_ADDRESS, val);
inputs:
New value for addressing mode
0 = 28-bit
1 = 48-bit
2 = 48-bit doing 28-bit
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 2]
EBUSY Controller busy
EIO Drive does not support lba48 mode.
HDIO_SET_IDE_SCSI
usage:
long val;
ioctl(fd, HDIO_SET_IDE_SCSI, val);
inputs:
New value for scsi emulation mode (?)
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_SET_SCSI_IDE
Not implemented, as of 2.6.8.1
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