USB device not available in a guest using more than 1 CPU

[Ludovic]

If I configure my guest OS to use more than 1 CPU then I can't use my USB device. I have a iMac model iMac11,1 with a Intel Core i7 (4 CPU with 2 threads each)

The USB device is a CCID smart card reader with vID=0x08E6 and pID=0x3437. The device works great if the guest uses only 1 CPU. But I get errors if I configure VirtualBox to use 2 or more CPU for the guest. The errors reported by the kernel are:

[   56.092448] usb 2-1: new full speed USB device using ohci_hcd and address 2
[   62.637182] atkbd.c: Spurious NAK on isa0060/serio0. Some program might be trying access hardware directly.
[   71.249524] usb 2-1: device descriptor read/64, error -110
[   86.512425] usb 2-1: device descriptor read/64, error -110
[   86.809503] usb 2-1: new full speed USB device using ohci_hcd and address 3
[  101.976574] usb 2-1: device descriptor read/64, error -110
[  117.240584] usb 2-1: device descriptor read/64, error -110
[  117.536353] usb 2-1: new full speed USB device using ohci_hcd and address 4
[  122.578952] usb 2-1: device descriptor read/8, error -110
[  127.698748] usb 2-1: device descriptor read/8, error -110
[  127.996433] usb 2-1: new full speed USB device using ohci_hcd and address 5
[  133.042903] usb 2-1: device descriptor read/8, error -110
[  138.161658] usb 2-1: device descriptor read/8, error -110
[  138.264556] hub 2-0:1.0: unable to enumerate USB device on port 1

and the lsusb command line tools is locked until the kernel gives up enumerating the device.

I have the problem with Debian testing/squeeze and also with Ubuntu 10.04. It is quiet easy to reproduce.

I also tried with Windows 7 and the device is visible with 1 CPU but not with a 2 CPU guest. So the problem is not limited to a Linux guest or the Linux kernel.

Since the problem is not linked to the guest OS it must be in VirtualBox itself.