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USB MSD are not marked as removable
Filed from Fedora bug: https://bugzilla.redhat.com/show_bug.cgi?id=589130
Guests can access USB Mass Storage Device, but fail to mark them as removable.
danpb has mentioned that Linux gets this information from SCSI INQUIRY response. So it's up to the USB Mass Storage Device to decide whether or not it wants to have a removable medium.
The SCSI INQUIRY RMB (removable medium bit) tends to be set on modern USB Mass Storage Devices. Of course they don't actually have a removable medium.
One side-effect of setting this bit is that Windows Auto-Run will work if RMB=0 but not work if RMB=0. Also, on RMB=1 devices only the first partition is displayed by Windows - you can't have more than one partition on the device.
For more information, see: http://www.microsoft.com/whdc/connect/usb/usbfaq.mspx
So at the end of the day, it's up to QEMU whether or not to mark USB MSDs as having removable media. Since modern devices tend to set RMB=1, we probably should too.
"One side-effect of setting this bit is that Windows Auto-Run will work if RMB=0 but not work if RMB=0" should read "but not work if RMB=1".
A sampling of physical USB devices:
1. Noname 2GB USB stick: RMB=1
2. Nexus One USB storage: RMB=1
3. LaCie USB harddisk: RMB=0
I suspect there's no setting that will satisfy everyone here. It makes sense for a USB harddisk to set RMB=0 because that allows you to put on more than one partition under Windows.
Stefan, you fixed this in QEMU 24 Jan 2011 so this bug can be marked as Fixed Released?
SEE: http://lists.gnu.org/archive/html/qemu-devel/2011-01/msg02425.html
Append ",removable=on" to a device definition for USB Mass Storage Devices to override the removable bit (but off by default):
> qemu -usb
> -drive if=none,file=test.img,cache=none,id=disk0
> -device usb-storage,drive=disk0,removable=on
However, I cannot see a way to set "removable=on" for usb-storage devices started via libvirt (in 12.04, with libvirt-bin 0.9.8-2ubuntu17.1 and virt-manager 0.9.1-1ubuntu5.1).
So, is a feature request required for virt-manager to expose this option for virtual disks (default to 'on' for bus='usb') and add support to libvirt's XML to set "removable=on" ?
On Mon, Jul 2, 2012 at 4:04 PM, Sebastian Malcolm
<email address hidden> wrote:
> Stefan, you fixed this in QEMU 24 Jan 2011 so this bug can be marked as
> Fixed Released?
Yes
> However, I cannot see a way to set "removable=on" for usb-storage
> devices started via libvirt (in 12.04, with libvirt-bin
> 0.9.8-2ubuntu17.1 and virt-manager 0.9.1-1ubuntu5.1).
>
> So, is a feature request required for virt-manager to expose this option
> for virtual disks (default to 'on' for bus='usb') and add support to
> libvirt's XML to set "removable=on" ?
Yes, I just checked libvirt.git/master and cannot see a way to set the
removable option. I'm afraid libvirt also needs changes.
Stefan
Setting status to "Fix released" according to comment #5 (if there is something left to do for libvirt, please consult their bugtracker instead)
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