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Last updated October 2005 17
A. The VCO is a composite USB 2.0 device. If the BIOS does not support (or supports in a limited fashion) USB 2.0 composite devices,
then the VCO can not work with it.
Q. Why can’t I use a VCO to access a computer’s BIOS when I can hook up a keyboard, mouse, USB CDRom, and USB Mass Storage
Device to a USB hub attached to the same computer and they work?
A. The VCO is a composite USB 2.0 device. A USB hub acts as a compound device. The USB specification (and BIOS support) for
composite devices and compound devices are different, therefore it is possible for one to be supported, but not the other.
Q. Why doesn’t my device show up in the Linux VM tool on the client computer?
A. The Linux VM tool reads the fstab and mtab to determine what to show. If your device is not listed in one of these two places, it
will not show up.
Q. Why can I use the VCOs capabilities once the OS has loaded, but not before?
A. Modern operating systems have USB drivers. When the BIOS detects an OS level driver loaded for the USB controller, it hands full
control of that controller to the OS.
Q. Why can I only see the first partition on my USB hard drive when it is mapped via VM?
A. The USB specification has several different device types that a USB device can identify itself as. Based upon the device type the
USB device enumerates as, the OS will react differently to it. To allow enumeration at boot but still have the ability to connect and
disconnect Virtual Media as needed, a device type of Mass Storage Device must be used. Windows only supports reading from the
first partition on a Mass Storage Device.
Q. Why can’t I see a USB device attached to the appliance when I am using a remote connection (or corollary, why can’t I see my CD-
ROM drive from OSCAR)?
A. For conditions of security, VM only allows you to access devices that are in your physical control at the time the VM session is
began. Since there is no way to determine if the KVM appliance and client computer are in the same spot, the KVM appliance will
only allow people accessing VM via OSCAR to connect to a USB device attached to the KVM appliance and people accessing VM via
a remote connection to only access media on the client computer creating the VM session.
Q. The BIOS seems to see everything, but I can’t use the keyboard. Why?
A. Since the VCO is a composite device, it can only negotiate one rate for all the pieces it enumerates as. This means that the
keyboard has to enumerate at high speed (480Mb/s). Some BIOSs can not handle a keyboard that negotiates at higher than low
speeds, so the keyboard section of the VCO will not work.