As such, a firmware defined interface is used to control the virtual device from interpreted machine language instructions. As the reader will appreciate an access mechanism will have to be 64 bit capable to write and read from registers located in MMIO space above 4 GB. While embodiments of the present invention are described in reference to an ACPI configuration management system, the embodiments are not limited to use with ACPI.
The processor represents a processing unit of various architectures. Embodiments of the invention can be implemented in a multi-processor or single processor system or computing device. Embodiments described herein can similarly be implemented in a distributed computing network environment, as the same are known and understood by one of ordinary skill in the art.
The embodiments are not limited to the examples given herein. The host bridge chipset includes a number of interface circuits to allow the host processor to access the system memory and the PCI bus The system memory represents one or more mechanisms for storing information.
The system memory may be loaded with an operating system OS , e. Examples of operating systems include, but are not limited to, Windows, Mac, Unix, Linux, etc. The system memory further includes a memory management system , e. The system memory may also contain additional software as the same will be known and understood by one of ordinary skill in the art. The memory management system includes elements such as virtual memory data structures associated with various processes to support the management of memory in connection with program applications being executed by the processor That is, as one of ordinary skill in the art will appreciate, the memory management system includes programs, code, data, look-up tables, etc.
Examples of PCI devices can include printers, removable disk storage and databases, facsimiles, scanners, network interface devices, media interface devices, etc. An example embodiment of the present invention is directed to devices which can be mapped to memory and thus can include circuitry cards to controllers which control the operation of the above mentioned PCI devices. For clarity, reference is made in this application to memory addresses.
Embodiments, however, are not limited to these examples. When implemented in firmware, the embodiments of the present invention are the code segments to perform particular tasks. A computer readable medium may include any medium that can store or transfer information. The computer data signal may include any signal that can propagate over a transmission medium such as electronic network channels, optical fibers, air, electromagnetic, RF links, etc.
The code segments may be downloaded via computer networks such as the Internet, Intranet, etc. The system or computing device can operate in a networked environment, e. As shown in FIG. The kernel can be generally considered as one or more software modules that are responsible for performing many operating system functions. One such function is passing information between the application programs and the lower level components of the ACPI system , such as various device drivers e.
Various device drivers interface with and generally control the system hardware , e. ACPI control methods are written in an interpreted language, i. The purpose of ACPI control methods is to interact with the system hardware, e. An operation region is an ACPI data object where read or write operations to the object are performed in some hardware space. In other words, operation regions represent some memory space that contains hardware registers for exclusive use by ACPI control methods.
An operation region includes established fields that represent registers in the hardware. In the past, there were only five defined operation regions that the ACPI driver set up during boot. According to the various embodiments, a new operation region is described to facilitate firmware controlled interaction with particular virtual devices.
The same is described in more detail below in connection with FIG. An operation region has identifying value s and a handler that performs accesses to various offsets in that operation region space. The above mentioned operation regions are assigned identifying values by the ACPI specification, e.
The ACPI specification also allows vendors to define and handle their own operation regions by using identifying hexadecimal values between 0x80 and 0xff. As the reader will appreciate, programming variables are structures that hold data and are uniquely named by the programmer. Variables are used to hold control and identifying values. A local variable includes values that are referenced only within the subprogram, function or procedure the variable is defined in.
A global variable is one that can be used by all modules and functions in the program. Later, before control methods access fields within the operation region, they should first check that namespace global variable to be sure that it contains the value indicating that the operation region has been enabled by the operating system. Certain operating systems, in FIG. The operation region handler itself performs the accesses to the system memory space.
The operation region handler is passed the offset, i. That is, the PCI driver detects bus, e. Communication with an operation region invokes the ACPI driver , which then to talks to the operation region handler associated with the operation region to complete the requested access.
Embodiments, however, are not so limited. Consider further that the ASIC e. According to various embodiments, an operation region is defined which represents the address space and offsets of a virtual device and when the address space and offsets of the virtual device are accessed they provide an interface, i.
In this example embodiment, chipsets implement power control for enabling hotplug as registers that are mapped to MMIO above 4 GB and need to be accessed atomically. Thus, in this example, these chipset registers are indirectly accessed through the virtual device and the AML does not have to talk to the chipset directly, which would involve a 64 bit access mechanism.
Instead, to achieve the 64 bit access, the virtual device and associated operation region are defined by firmware with the ACPI namespace, e.
There will be one virtual device per partition and one operation region per virtual device In effect, there will be no problem of one access to a virtual device corrupting another access if control methods are executed atomically, e.
Atomic changes are handled completely or not at all. That is, the acceptable outcomes are that all of the operations complete, or none of them do; partial completion is unacceptable.
According to various embodiments, the operation region handler being accessed will enable writes and reads above 4 GB in atomic fashion from ACPI control methods within the ACPI namespace. In the example given herein there are two notions of atomic.
The first involves writing a bit quantity as one chunk atomically as designed by a particular chipset. The second involves accessing the virtual device as a sequence. The virtual device will enable firmware control methods to write to any device that resides above 4 GB by allowing access to its control methods for writing the operation region. The operation region handler will handle read and write requests to the operation region described more in connection with FIG.
The operation region handler will use a globally unique identifier GUID as well as an operation region identifier from the hardware vendor range i. In this example embodiment, the operation region handler in FIG.
In this example, and according to the embodiments, the device is a virtual device defined, as well as the associated operation region, by firmware in the ACPI namespace.
In the above example, the need for the use of the new operation region handler is the result of an earlier ACPI version AML interpreter being a 32 bit interpreter and not 64 bit capable. Hence, in this example, the embodiments provide a way to access memory above 4 GB and read and write 64 bit data atomically as desired. Hello, Jay! Thanks for chatting with us. Ask me anything. Confirm End Chat Go Back. Chat Ended. Close Chat Save Transcript. OK Download. This new approach has additional benefits: By using PDF created by the ERP system, those documents can be archived for later retrieval and reprinting PDF can be created at the intended print size — eliminating the need to scale documents, which can induce bar code scanning issues Zebra regularly updates Virtual Devices, so revisit this page to obtain updates.
Back to Results Derived virtual devices: a secure distributed file system mechanism This paper presents the design of derived virtual devices DVDs. DVDs are the mechanism used by the Netstation Project to provide secure shared access to network-attached peripherals distributed in an untrusted network environment. The security enforced at the device through the DVD mechanism includes resource boundary checking, user authentication, and restricted operations, e.
To illustrate the application of DVDs, we present the interactions between a network-attached disk and a file system designed to exploit the DVD abstraction. We further discuss third-party transfer as a mechanism intended to provide for efficient data transfer in a typical NAP environment.
We show how DVDs facilitate third-party transfer, and provide the security required in a more open network environment.
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