---
name: "usfs"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/usfs"
---

# usfs(4)

USB device side support for bulk only transport mass storage

## NAME

**usfs** – USB device side support for bulk only transport mass storage

## SYNOPSIS

To compile this driver into the kernel, place the following lines in your kernel configuration file:

**device usb** **device usfs**

Alternatively, to load the driver as a module at boot time, place the following line in [loader.conf(5)](/loader.conf/5.md):

```
usfs_load="YES"
```

## DESCRIPTION

This driver is obsolete. Users are advised to use [cfumass(4)](/cfumass/4.md) instead.

The **usfs** driver provides support for emulating an USB mass storage device when the USB stack is activated in USB device side mode (the [usb\_template(4)](/usb_template/4.md) module is loaded and the *hw.usb.template* sysctl is set to 0).

Upon attach the driver creates a RAM disk which can be read and written.

## SEE ALSO

[cfumass(4)](/cfumass/4.md), [umass(4)](/umass/4.md), [usb(4)](/usb/4.md), [usb\_template(4)](/usb_template/4.md)

## HISTORY

The **usfs** driver appeared in FreeBSD 8.0.