Electrical computers and digital data processing systems: input/ – Intrasystem connection – System configuring
Reexamination Certificate
1998-01-20
2001-06-05
Chan, Eddie (Department: 2983)
Electrical computers and digital data processing systems: input/
Intrasystem connection
System configuring
C710S120000, C710S120000, C710S108000, C710S008000, C710S010000, C713S001000
Reexamination Certificate
active
06243775
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to techniques for increasing the number of user-definable configuration registers available in a computer system. More particularly, the present invention relates to a procedure for making unused configuration memory space available for use as configuration registers.
BACKGROUND OF THE INVENTION
In computer systems employing the commonly-used Peripheral Component Interconnect (PCI) bus, the PCI architecture makes available configuration registers that can be used for implementing various logic and control functions. The configuration registers are typically programmed and accessed by the device that implements a particular function or feature. Often, the number of configuration registers available is sufficient for a given programming task. However, for implementations of some tasks, the number of configuration registers is too small, making PCI configuration registers a scarce resource. Increasing the number of PCI configuration registers is difficult, however, because the PCI standard requires that configuration registers be addressed in a specified manner, and conform to requirements of other software and hardware. Thus, there exists a need for an effective method for increasing the number of available configuration registers, while also maintaining compatibility with applicable bus standards or other standards.
SUMMARY OF THE INVENTION
The present invention relates to techniques for increasing the number of user-definable configuration registers, such as in a PCI-based computer system. In some embodiments, the present invention uses a non-existent device function to provide additional user definable configuration registers, while still maintaining compatibility with applicable standards or conventions.
In one embodiment of the invention, the invention relates to a computer comprising: (a) a processor; (b) a PCI bus attached to the processor through bridge logic; (c) configuration memory space that is accessible to the processor and that is allocated for devices attached to the PCI bus, wherein each PCI device has configuration space allocated for a plurality of functions; and (d) a PCI device attached to the PCI bus that has memory allocated in the configuration memory space for a first function for the PCI device and for a second function for the PCI device. The PCI device includes hardware for carrying out the first function, where the hardware for carrying out the first function accesses (i) configuration registers in the configuration memory space that corresponds to the first function and also (ii) configuration registers in the configuration memory space that corresponds to the second function.
In another embodiment of the present invention, the present invention relates to a method of configuring and using a device, where the device has configuration memory space allocated to it for a plurality of functions. At least one of the plurality of functions is implemented by the device, and at least one of the plurality of functions is not implemented by the device. The method comprises the acts of: (a) storing data in a header portion of the configuration space allocated to the function that is not implemented by the device, wherein the data indicates that the function is not implemented; (b) programming a register that is in the remaining portion of the configuration space allocated to the function that is not implemented by the device; and (c) accessing the programmed register.
Additional embodiments and features, and the nature of the present invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims, and to the several drawings herein.
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Chan Eddie
Dorsey & Whitney LLP
Micro)n Technology, Inc.
Monestime Mackly
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