[blfs-support] Assign USB device to a Guest VM - permission problem

Cliff McDiarmid cliffhanger at gardener.com
Sun Oct 26 04:28:44 PDT 2014

Sent: Saturday, October 25, 2014 at 11:03 AM
From: "Eugen Barticel" <eugenbart66 at gmail.com>
To: "BLFS Support List" <blfs-support at lists.linuxfromscratch.org>
Subject: Re: [blfs-support] Assign USB device to a Guest VM - permission problem

>I think you should add user to vbox or vboxuser groups as well, if you didn't already.
>On Sat, Oct 25, 2014 at 5:40 AM, Cliff McDiarmid <cliffhanger at gardener.com> wrote:>Hi
>Can anyone help here with a VM problem? 
>I'm using Qemu, with KVM, on LFS 7.5(with systemd)to run a virtual machine and need to assign a usb device(gps) from the host to guest.  
>If I run the VM from root, with the necessary arguments, then everything works fine.
>But I want to run it from the user.  And here is where the problem lies.  I've included a udev rule for the device in the host like this:

>#Prolific Technology GPS
>SUBSYSTEMS=="usb", ATTRS{idVendor}=="067b", ATTRS{idProduct}=="2303", MODE="0644", GROUP="usb"
>I've made sure the user is part of the 'usb' group, but I still get the following error:
>'libusbx: error [_get_usbfs_fd] libusbx couldn't open USB device /dev/bus/usb/003/003:
>Permission denied libusbx: error [_get_usbfs_fd] libusbx requires write access to USB device nodes'

>I've tried changing the 'mode', I shouldn't have to, but this makes no difference. 

Thanks Eugen,

You mean the kvm group?  User is a member of that.  Don't have vbox or vboxuser groups.

I had the rules.d file in /etc/udev/rules.d, so copied it to /lib/udev/rules.d/, this made no difference.


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