Hello Lew and all,

Lew Wolfgang wrote:
> After a lot of fiddling and non-deterministic behavior I isolated the
> problem to multiple mounting of the  usbfs filesystem.
As of VirtualBox 2.1.2 (with a couple of fixes in 2.1.4), USB on Linux
hosts should work without mounting /proc/bus/usb at all.  Judging from
the reports (like this thread), this does not work for everyone.  It
would be great if some of the people experiencing problems could help to
troubleshoot this.

First of all, I will briefly explain the technical background.  In order
for guests to access USB devices, they have to be able to read and write
the device nodes for those devices.  Those device nodes are now found
under /dev/bus/usb.  (To find out which node belongs to which device,
look for the device in the output of the "lshal" application.)

If everything is set up correctly, most of the USB device nodes (that
is, those that are not assigned to someone else by the system) should be
readable and writable to the group "vboxusers".  So users who want to
use USB in VirtualBox should of course be members of that group.  (BTW,
when a user becomes a member of a group in Linux, they have to log in
and out again before the change really takes effect.)  VirtualBox can
detect the devices even if the user can't read or write them - this is
when the devices are shown as "greyed out".

So, if things are not working, some things to look at for starters are:

* Does the group "vboxusers" exist, and which users are members?

$ cat /etc/group | grep vboxusers
vboxusers:x:1001:michael

* Logging in and out, or rebooting will guarantee that those users
really are members of the groups.
* Is the device node of the device you want to access readable and
writable for that group?  e.g.

$ ls -l /dev/bus/usb/001/001
crw-rw-r-- 1 root vboxusers 189, 0 2009-02-24 08:46 /dev/bus/usb/001/001

Knowing what is going wrong here would help to get this working properly.

Regards and thanks,

Michael

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