Driver for USB Mass Storage interface

Note: In order to start this driver, you must be logged in as root or have the right abilities, and the USB stack (io-usb-otg) needs to be running.


devb-umass [blk option[,option]...]
           [cam option[,option]...]
           [disk option[,option]...]
           [umass options[,option]...]

Runs on:

QNX Neutrino


Note: Use commas (,) to separate the options. You can put the blk, cam, disk, and umass groups of options in any order.
blk options
The blk options control If specified, they must follow the blk keyword. For more information, see
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.
Map the bounce buffer as PROT_NOCACHE (cache=off) or not (cache or cache=on).
Enable Logical Unit Number (LUN) scanning for the devices specified in mask. The mask is a hex bitmask specifying which IDs to scan for; the default is 0xffff.
Don't call ThreadCtl(_NTO_TCTL_IO_PRIV).
Enable CAM plug and play (i.e. don't exit at startup when no devices are found). The default is off.
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.
Be verbose: display full information about units (devices) on startup.
disk options
The disk options control the driver's interface to If specified, they must follow the disk keyword.
umass options
The umass options control the driver's interface to the USB device. If you've installed multiple devices, you can repeat these options for each device. Remember, however, to specify the umass keyword before each controller's set of options.
The bus number of the USB controller.
Specify the command timeout in ms. The default is 4 seconds.
The configuration number of the device.
Ignore the Command Status Wrapper. Some devices return invalid data for the CSW.
The USB address of the device.
The device ID of the device.
The particular interface number of the device.
Set the maximum number of bulk resets (default is 0). Once we reach this, the device will be disabled.
Set the maximum number of consecutive medium errors for devices that need to tweak the medium sense error. Beyond this limit, medium errors will return. The default is 10.
Set the polling thread interval, where num is the normal polling interval in ms, fpoll is the polling interval to use during startup (a faster rate), and fnum is how many times to poll using the second parameter. You can either specify the first parameter (without fpoll and fnum), or specify all three parameters. If you don't specify this option, there's no polling thread.
Connect to the specified USB stack. The default is /dev/usb/io-usb-otg.
Set the priority of the processing thread. The default is 21.
Set the path name of the SCSI passthrough interface (default none).
The vendor ID of the device.
Wait num of seconds for the USB stack. The default is 60 seconds.


The devb-umass driver is the driver for a USB mass storage interface.


The devb-umass driver may require the following abilities:

Use secpolmonitor to determine which abilities devb-umass is using on your specific system.

For more information on abilities, see procmgr_ability() in the C Library Reference.


Assume a USB controller, and list all connected devices:

devb-umass &

Assume a USB controller, and list/wait for all connected devices:

devb-umass cam pnp &