Driver for AHCI SATA interfaces (QNX Neutrino)

Note: You must be root or have the right abilities to start this driver.


devb-ahci [cam option[,option]...]
          [mem option[,option]...]
          [ahci option[,option]...]
          [blk option[,option]...] &

Runs on:

QNX Neutrino


Note: Use commas (,) to separate the options. You can put the cam, mem, ahci, and blk groups of options in any order.
cam options
The cam options control the common access methods:
Perform CPU cache invalidation after an I/O operation in a thread that's separate from the one that's notifying the upper layer. In some cases, and on some boards, this can provide a performance boost.
Specify the size of the driver's “bounce” buffer. The size argument can include a case-insensitve suffix that indicates the units: B (bytes; the default), K (kilobytes), M (megabytes), or P (pages). The bounce buffer is used if a specific piece of hardware can't directly access io-blk block cache buffers. The most common example is chips that don't support scatter-gather. The default is 32 KB.
Specify to perform cache invalidation or cache flushes on the buffers. Map the bounce buffer as PROT_NOCACHE (cache=off) or not (cache or cache=on).
Enable Logical Unit Number (LUN) scan for the devices specified in mask. The mask is a hex bitmask specifying which IDs to scan for; the default is 0x00.
Don't call ThreadCtl(_NTO_TCTL_IO_PRIV).
Be quiet: don't display any information on startup.
Specify the number of times to retry an operation before indicating to the filesystem that an I/O error occurred. The default is 10.
Operate as the specified user and group IDs. The driver retains the necessary process-manager abilities.
Increase the verbosity of the low-level hardware driver.
mem options
The typed memory name to use.
Note: It's up to the startup to set up typed memory. For more information, see Typed memory in the “Interprocess Communication (IPC)” chapter of the System Architecture guide.
ahci options
The ahci options control the driver's interface to the AHCI controller. If you've installed multiple controllers, you can repeat these options for each controller. Remember, however, to specify the ahci keyword before each controller's set of options.
  • Interface-specific options:
    The device ID of the controller.
    The address of the interface.
    The interrupt used by the controller.
    Don't use busmastering. Specify this option if you want to disable DMA.
    Set the number of ports.
    The PCI index of the controller in the machine, where index is a value between 0 and the number of adapters.
    Set the ports implemented bitmap. For example, pi=0x4 specifies port 2.
    Specify options for device on port N.
    Set the priority of the processing thread. The default is 21.
    Power down the device on exit.
    Set the reset timeout, in seconds. The default is 40.
    Set the I/O request timeout, in seconds. The default is 10.
    The vendor ID of the controller.
  • Device-specific options:
    Use Cylinder-Head-Sector mode. The default is LBA.
    Specify the drive geometry.
    Set multiblock mode, using the given number of blocks per interrupt.
    Don't use busmastering. Specify this option if you want to disable DMA.
    Report the device as being nonremovable.
    Enable or disable device read-ahead, where state is on or off.
    Enable SMART monitoring. If there are problems with the drive, the driver puts a message in the system log (see slog2info and slogger2).
    Note: The message is logged only at startup.

    There currently isn't a mechanism to retrieve SMART data.

    Set the device verbosity level.
    Enable or disable device write cache, where state is on or off.
blk options
The blk options control If specified, they must follow the blk keyword.


The devb-ahci supports the Intel AHCI SATA controller ith the following device IDs:

Note: You need to enable AHCI mode in the BIOS.


Detect all SATA controllers, and list all connected devices:

devb-ahci &

Detect all SATA controllers and use a typed memory region named dma (which the startup must have set up):

devb-ahci mem name=/ram/dma &


The devb-ahci driver causes to adopt various block special devices under /dev. These devices are normally named hdn, where n is the physical unit number of the device.

This driver could also require the following shared objects:

Binary Required For hard-disk access. Always

Exit status:

The devb-ahci driver terminates only if an error occurs during startup, or if it has successfully forked itself upon startup because it hadn't been initially started in the background.

The devb-ahci driver wasn't started in the background and therefore forked itself. The original process terminated with a zero exit status, the forked process continued.
> 0
An error occurred during startup.


Unless overridden with the blk automount= option (see, devices are mounted as:

Device Mountpoint Filesystem type
/dev/hd0t177 /hd qnx6
/dev/hd0t6 /dos dos
/dev/hd0t11 /dos dos

While there's no limit to the size of a disk or partition, the limit on I/O (i.e., the lseek(), read() and write() functions) depends on the type of filesystem mounted and on whether you use the 32- or 64-bit versions of these functions. This I/O limit has no effect on the partition size for mounted filesystems. The maximum number of blocks is 232.

Known supported functions include:

chmod(), chown(), close(), closedir(), creat(), devctl(), dup(), dup2(), fcntl(), fpathconf(), fstat(), lseek(), mkdir(), mkfifo(), mknod(), open(), opendir(), pathconf(), read(), readdir(), readlink(), rewinddir(), rmdir(), stat(), symlink(), unlink() (not supported for directories), utime(), write()

Note that certain calls (such as pipe(), as well as read() and write() on FIFOs) may require the pipe manager.