UMASS(4)               FreeBSD Kernel Interfaces Manual               UMASS(4)

NAME

     umass - USB Mass Storage Devices driver

SYNOPSIS

     device da
     device scbus
     device pass
     device usb
     device umass

     In loader.conf(5):
     umass_load

DESCRIPTION

     The umass driver provides support for Mass Storage devices that attach to
     the USB interface.

     If the appropriate hardware is detected, the driver will be loaded
     automatically by devmatch(8).  To load the driver manually at boot time,
     use the umass_load command at the loader(8) prompt, or add it to
     loader.conf(5).

     To use the driver in a custom kernel, usb(4) and at least one of uhci(4),
     ohci(4), ehci(4), or xhci(4) must be configured in the kernel.
     Additionally, since umass uses the SCSI subsystem and sometimes acts as a
     SCSI device, it requires da(4) and scbus(4) to be included in the kernel.

HARDWARE

     The umass driver supports USB Mass Storage devices such as:

     o   USB thumb drives
     o   USB hard disk drives
     o   USB floppy drives

EXAMPLES

     Rescan all slots on a multi-slot flash reader, where the slots map to
     separate LUNs on a single SCSI ID:

           camcontrol rescan 0:0:0
           camcontrol rescan 0:0:1
           camcontrol rescan 0:0:2
           camcontrol rescan 0:0:3

     Typically only the first slot will be enabled at boot time.  This assumes
     that the flash reader is the first SCSI bus in the system and has 4
     slots.

SEE ALSO

     cfumass(4), ehci(4), ohci(4), uhci(4), usb(4), xhci(4), camcontrol(8)

HISTORY

     The umass driver appeared in FreeBSD 4.3.

AUTHORS

     The umass driver was written by MAEKAWA Masahide <bishop@rr.iij4u.or.jp>
     and Nick Hibma <n_hibma@FreeBSD.org>.

     This manual page was written by Nick Hibma <n_hibma@FreeBSD.org>.

FreeBSD 15.1-STABLE-HBSD        October 9, 2025                       UMASS(4)