NAME
cfumass —
USB device side support for Mass
Storage Class Transport
SYNOPSIS
This driver can be compiled into the kernel by placing these lines in the kernel configuration file:
device usb
device usb_template
device ctl
device cfumassThe driver module can also be loaded at boot by adding this line to loader.conf(5):
cfumass_load="YES"
DESCRIPTION
Thecfumass driver provides device side support for
emulating an USB mass storage device compliant with the USB Mass Storage Class
Bulk-Only (BBB) Transport specification, implemented as a
ctl(4) frontend driver.
To use cfumass:
- cfumass(4) must be loaded as a module or compiled into the kernel.
- The USB Mass Storage template must be chosen by setting the hw.usb.template sysctl to 0.
- The USB OTG port must be working in USB device-side mode. This happens automatically upon connection to a USB host.
- There must be a ctl(4) LUN configured for the cfumass port.
Upon loading, the driver creates a
ctl(4) port named cfumass, presenting the
first LUN mapped for that port - usually LUN 0 - to the USB host. See
ctl.conf(5) and
ctld(8) for details on configuring the LUN. See the
cfumass_enable and
cfumass_dir
rc(8)
variables in
rc.conf(5) for an automated way to configure it at boot.
SYSCTL VARIABLES
These variables are available as both sysctl(8) variables and loader(8) tunables:
- hw.usb.cfumass.debug
- Verbosity level for log messages from the
cfumassdriver. Set to 0 to disable logging or 1 to warn about potential problems. Larger values enable debugging output. Defaults to 1. - hw.usb.cfumass.ignore_stop
- Ignore START STOP UNIT SCSI commands with START and LOEJ bits cleared. Some initiators send that command to stop the target when the user attempts to gracefully eject the drive, but fail to start it when the drive is reconnected. Set to 0 to handle the command in a standards-compliant way, 1 to ignore it and log a warning, or 2 to ignore it silently. Defaults to 1.
- hw.usb.cfumass.max_lun
- Max LUN number to report to the initiator (USB host). Must be between 0 and 15. Some initiators incorrectly handle values larger than 0. Defaults to 0.
SEE ALSO
ctl(4), umass(4), usb(4), usb_template(4), ctl.conf(5), ctld(8)
HISTORY
The cfumass driver first appeared in
FreeBSD 11.1.
AUTHORS
The cfumass driver was developed by
Edward Tomasz Napierala
<trasz@FreeBSD.org>
under sponsorship from the FreeBSD Foundation.