Systems and methods for supporting device access from multiple operating systems

• US 7,581,229 B2
• Filed: 03/11/2005
• Issued: 08/25/2009
• Est. Priority Date: 03/11/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Nicholas, Andrew Ernest, Watkins, Douglas A.
• Primary Examiner(s): Nguyen; Van H
• Application Number:
  US11/078,065
• Publication Number:
  US 20060206904A1
• Time in Patent Office: 1,628 Days
• Field of Search: 719/310, 719319-321, 719/330, 718/1, 703/23, 703/27, 709/223, 709/224
• US Class Current: 719/321
• CPC Class Codes: G06F 9/45537 Provision of facilities of other operating environments, e.g. WINE I/O emulation G06F13/105

Abstract

A host operating system can take ownership of a device. The host can project the presence of a device proxy (VDP) into a guest operating system. The VDP provides a set of device functions corresponding to the particular device class. Interactions with the VDP in the guest are forwarded to a Virtual Service Provider (VSP) in the host. The VSP maps a set of device class functions onto physical devices through a hardware abstraction and emulation layer. Functions supported directly by a physical device can be delivered to the device by the hardware abstraction layer (HAL). Functions not directly supported can be implemented through the hardware emulation layer (HEL). A uniform and robust set of functions may be made available in the guest regardless of hardware changes in the host, migration to a new host, or use of the device by other competing operating systems.

Claims

1. A computer system comprising:

computer hardware configured to execute a first operating system, the computer hardware comprising a hardware device;

a virtual machine configured to execute a second operating system;

the hardware device being configured to be controlled by said first operating system via a driver installed on said first operating system;

the first operating system including a service provider, said service provider configured to;

determine a set of functions to expose to the second operating system, the set of functions including functions that the hardware device is configured to perform and functions that software is configured to emulate,

expose the set of determined functions to the second operating system via a proxy driver instantiated in the second operating system, the service provider configured to receive function invocations from the second operating system via the proxy driver and

send function invocations that are directly supported by said hardware device to the hardware device and function invocations that software is configured to emulate to an emulator.

2. The computer system of claim 1, further comprising a hardware abstraction and emulation layer between said service provider and said driver installed on said first operating system, wherein the hardware abstraction and emulation layer provides a first plurality of functions that are directly supported by the hardware device, and a second plurality of functions that require execution of software to carry out substantial aspects of a corresponding request.

3. The computer system of claim 1 wherein said proxy driver is configured by said service provider to represent said at least one function of said hardware device to a plurality of operating systems.

4. The computer system of claim 1 wherein the service provider maintains an artificial device state of the hardware device on behalf of the second operating system.

5. The computer system of claim 1 wherein the service provider comprises a component for determining if the hardware device is exchanged for a second hardware device.

6. The computer system of claim 1, further comprising a network connection to a second computer system, wherein said second operating system is configured to be migrated across said network connection to said second computer system while maintaining a set of driver commands at said first operating system on behalf of said second operating system.

7. A computer readable storage medium having instructions for representing by a first operating system a hardware device in a second operating system, said instructions comprising:

instructions for a first operating system that includes a service provider, the service provider including instructions for;

determining a set of functions to expose to a second operating system executing in a virtual machine, the set of functions including functions that a hardware device is configured to perform and functions that software is configured to emulate, the hardware device being controlled from the first operating system via a driver installed in the first operating system;

exposing the set of determined functions to the second operating system via a proxy driver instantiated in the second operating system, the service provider configured to receive function invocations from the second operating system via the proxy driver and

sending function invocations that are directly supported by said hardware device to the hardware device and function invocations that software is configured to emulate to an emulator.

8. The computer readable storage medium of claim 7 wherein said instructions for sending function invocations that are directly supported by said hardware device and function invocations that are emulated by software to an emulator comprise instructions for requesting a hardware abstraction and emulation layer to perform the function invocations, wherein the hardware abstraction and emulation layer provides a first plurality of functions that are directly supported by the hardware device, and a second plurality of functions that require execution of software to carry out substantial aspects of a corresponding request.

9. The computer readable storage medium of claim 7, further comprising instructions for configuring by said first operating system said proxy driver to represent said at least one function of said hardware device to a plurality of operating systems.

10. The computer readable storage medium of claim 7, further comprising instructions for maintaining by said first operating system an artificial device state of the hardware device on behalf of the second operating system.

11. The computer readable storage medium of claim 7, further comprising instructions for determining if the hardware device is exchanged for a second hardware device.

12. The computer readable storage medium of claim 7 wherein said instructions for communicating remain operable when said second operating system is migrated from a first computer system to a second computer system.

13. The computer readable storage medium of claim 7, further comprising instructions for switching by said first operating system from the use of said hardware device to the use of a second hardware device.

14. A method for representing by a first operating system a hardware device in a second operating system, comprising:

determining, by a service provider executing within said first operating system, a set of functions to expose to a second operating system executing in a virtual machine, the set of functions including functions that a hardware device is configured to perform and functions that software is configured to emulate, the hardware device being controlled from the first operating system via a driver installed in the first operating system;

configuring by said first operating system a proxy driver to expose said set of functions to said second operating system;

exposing the set of determined functions to the second operating system via a proxy driver instantiated in the second operating system, the service provider configured to receive function invocations from the second operating system via the proxy driver and

sending function invocations that are directly supported by said hardware device to the hardware device and function invocations that software is configured to emulate to an emulator.

15. The method of claim 14 wherein said sending function invocations that are directly supported by said hardware device and function invocations that are emulated by software to an emulator comprises requesting a hardware abstraction and emulation layer to perform the function invocations, wherein the hardware abstraction and emulation layer provides a first plurality of functions that are directly supported by the hardware device, and a second plurality of functions that require execution of software to carry out substantial aspects of a corresponding request.

16. The method of claim 14, further comprising configuring by said first operating system said proxy driver to represent said at least one function of said hardware device to a plurality of operating systems.

17. The method of claim 14, further comprising maintaining by said first operating system an artificial device state of the hardware device on behalf of the second operating system.

18. The method of claim 14, further comprising determining if the hardware device is exchanged for a second hardware device.

19. The method of claim 14 wherein said communicating occurs despite a concurrent migration of said second operating system from a first computer system to a second computer system.

20. The method of claim 14, further comprising switching by said first operating system from using said hardware device to using a second hardware device.