[vbox-dev] Linux PCI-passthrough kernel module cleanup

Michal Necasek michal.necasek at oracle.com
Fri Sep 22 11:58:39 UTC 2017

In our experience, the xHCI emulation in VirtualBox works well for USB devices like webcams and headsets, and some professional audio devices are reported to work as well (e.g. Focusrite Scarlett Solo, Roland Duo-Capture). Not every device works, but Linux usbfs is not slow. 

Whether VMs are suitable for any real-time workloads at all is a different question. 


----- Original Message ----- 
From: a.h.yakovlev at gmail.com 
To: michael.thayer at oracle.com 
Cc: vbox-dev at virtualbox.org 
Sent: Tuesday, September 5, 2017 7:42:09 AM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna 
Subject: Re: [vbox-dev] Linux PCI-passthrough kernel module cleanup 

Hi Michael, 

Well, basically, I'm running WIndows 10 guest and have a few USB devices (professional audio card + web cams), which do not work in the guest at all (though they appear in Windows and have correct setup). Since other USB devices work fine (like USB mass storage), I was wondered why it so. Brief investigation on VBox sources showed, that it seems, that VBox uses USBFS-based interface for backend on Linux host. In general case, it does not suit for real-time data (like audio/video streams). In such case it's better to have a Linux kernel driver, which handles all actual URB traffic, and backend make direct calls to that driver (like vhost-based drivers do). As I can understand, VBox allows to make direct call to kernel modules through COM-interfaces. That's why I decided to play with it and replace current implementation of Linux USBProxyDevice implementation. :) 

Best regards, 

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