USB is short for Universial Serial BUS. There are currently five variants of USB. The new USB stack in FreeBSD -current supports Low, Full and High speed USB devices in Host- and Device Mode.

• Low Speed USB
• Full Speed USB
• High Speed USB
• Super Speed USB (not supported yet)
• Wireless USB (not supported yet)

This page describes HPSUSB/'USB2' which is available in FreeBSD 8-CURRENT.

• Q: hald is using 100% CPU
• A: You need to re-link hald to use /usr/lib/libusb20.so which is now part of the base distribution.

• Q: xsane does not detect my scanner
• A: You need to re-link xsane to use /usr/lib/libusb20.so which is now part of the base distribution.

• Q: Do I need to recompile the software before it can use libusb20 instead of libusb-0.1.x?
• A: No, libusb20 is binary compatible with libusb-0.1.x.

• Q: How do I re-link an application to use libusb20?
• A: Add “-lusb20” when linking, modify “libmap.conf” or run the following commands like SuperUser:

mv -i /usr/local/lib/libusb-0.1.so.8 /root/
mv -i /usr/local/lib/libusb.a /root/
ln -s /usr/lib/libusb20.so.1 /usr/local/lib/libusb-0.1.so.8
ln -s /usr/lib/libusb20.a /usr/local/lib/libusb.a

• Q: How do I give other users access to my USB devices on my computer?
• A: Examples:

# This command gives access to a specific USB device given by BUS unit
# and device address, until the device is unplugged:
usbconfig -u xxx -a yyy set_owner user:group set_perm 0660

# This command gives permanent access to a specific 
# BUS unit and all sub devices:
usbconfig -u xxx set_owner user:group set_perm 0660

# This command gives permanent access access to any USB device:
usbconfig set_owner user:group set_perm 0660

# This command dumps the access restrictions:
usbconfig dump_access

# Also see
man usb2_core

• Q: I see the following error and USB stops working “Page offset was not preserved!”
• A: Try this patch:

http://perforce.freebsd.org/chv.cgi?CH=154181

• Q: I can't boot my Freesbie using USB2.
• A: Try this patch:

--- vfs_mount.c.orig    Mon Dec 22 14:43:36 2008
+++ vfs_mount.c Mon Dec 22 15:09:14 2008
@@ -58,6 +58,7 @@
 #include <sys/sysent.h>
 #include <sys/systm.h>
 #include <sys/vnode.h>
+#include <sys/cons.h>
 #include <vm/uma.h>
 
 #include <geom/geom.h>
@@ -1606,7 +1607,11 @@
 vfs_mountroot(void)
 {
        char *cp;
-       int error, i, asked = 0;
+       const char *rootdevname_orig;
+       int error;
+       unsigned int i;
+       unsigned char asked = 0; /* set if asked for mount point */
+       unsigned char timeout = 16; /* seconds */
 
        root_mount_prepare();
 
@@ -1624,6 +1629,10 @@
                asked = 1;
        }
 
+       /* store a copy of the initial root device name */
+       rootdevname_orig = ctrootdevname;
+ retry:
+
        /*
         * The root filesystem information is compiled in, and we are
         * booted with instructions to use it.
@@ -1674,12 +1683,27 @@
                if (!vfs_mountroot_try(ctrootdevname))
                        goto mounted;
        /*
-        * Everything so far has failed, prompt on the console if we haven't
-        * already tried that.
+        * Check if we should try more times.
+        */
+       if (timeout != 0) {
+               timeout--;
+               pause("WROOT", hz);
+               if (cncheckc() == -1) {
+                       /* no key press - try again */
+                       ctrootdevname = rootdevname_orig;
+                       goto retry;
+               }
+       }
+
+       /*
+        * Everything so far has failed, prompt on the console if we
+        * haven't already tried that.
         */
-       if (!asked)
+       if (!asked) {
+               printf("\n");
                if (!vfs_mountroot_ask())
                        goto mounted;
+       }
 
        panic("Root mount failed, startup aborted.");