Updated: April 19, 2023

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]...] 
          [fs_type options] &

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 If specified, they must follow the cam keyword.
mem options
The typed memory name to use. This option lets you restrict the driver to use memory only from a particular region, which is often necessary for DMA and smmuman. If you set this option, it can benefit performance to set the same option in the blk layer as well, depending on the size of the typed memory region. The cam layer will move data between the blk layer and the typed memory.
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.
fs_type options
The fs_type options control any filesystem (fs-*.so) module being loaded. Here, fs_type is the filesystem type, such as qnx6 for the Power-Safe filesystem. For the list of supported filesystem options, see the reference for the corresponding shared object. For example, for qnx6, see


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.