.\" Copyright (c) 2017 The FreeBSD Foundation
.\"
.\" This software was developed by Edward Tomasz Napierala under sponsorship
.\" from the FreeBSD Foundation.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.Dd April 21, 2018
.Dt CFUMASS 4
.Os
.Sh NAME
.Nm cfumass
.Nd USB device side support for Mass Storage Class Transport
.Sh SYNOPSIS
This driver can be compiled into the kernel by placing these lines in
the kernel configuration file:
.Bd -ragged -offset indent
.Cd "device usb"
.Cd "device usb_template"
.Cd "device ctl"
.Cd "device cfumass"
.Ed
.Pp
The driver module can also be loaded at boot by adding this line to
.Xr loader.conf 5 :
.Bd -literal -offset indent
cfumass_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
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
.Xr ctl 4
frontend driver.
.Pp
To use
.Nm :
.Bl -bullet
.It
.Xr cfumass 4
must be loaded as a module or compiled into the kernel.
.It
The USB Mass Storage template must be chosen by setting the
.Va hw.usb.template
sysctl to 0.
.It
The USB OTG port must be working in USB device-side mode.
This happens automatically upon connection to a USB host.
.It
There must be a
.Xr ctl 4
LUN configured for the
.Pa cfumass
port.
.El
.Pp
Upon loading, the driver creates a
.Xr ctl 4
port named
.Pa cfumass ,
presenting the first LUN mapped for that port - usually LUN 0 - to
the USB host.
See
.Xr ctl.conf 5
and
.Xr ctld 8
for details on configuring the LUN.
See the
.Cm cfumass_enable
and
.Cm cfumass_dir
.Xr rc 8
variables in
.Xr rc.conf 5
for an automated way to configure it at boot.
.Sh SYSCTL VARIABLES
These variables are available as both
.Xr sysctl 8
variables and
.Xr loader 8
tunables:
.Bl -tag -width indent
.It Va hw.usb.cfumass.debug
Verbosity level for log messages from the
.Nm
driver.
Set to 0 to disable logging or 1 to warn about potential problems.
Larger values enable debugging output.
Defaults to 1.
.It Va 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.
.It Va 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.
.El
.Sh SEE ALSO
.Xr ctl 4 ,
.Xr umass 4 ,
.Xr usb 4 ,
.Xr usb_template 4 ,
.Xr ctl.conf 5 ,
.Xr ctld 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 11.1 .
.Sh AUTHORS
The
.Nm
driver was developed by
.An Edward Tomasz Napierala Aq Mt trasz@FreeBSD.org
under sponsorship from the FreeBSD Foundation.