Method and apparatus for transmission and processing of virtual commands
First Claim
1. In a system comprising a CPU, a device that supports a plurality of virtual devices and address bus and data bus each coupled between the CPU and the device, a method for atomically transferring command and data information to the device having device logic comprising the steps of:
- transferring command data across the data bus to the device;
transferring address data across the address bus to the device in the same bus cycle with said command data, said address data comprising a device address, an address of a virtual device register, a type of command to be performed and an identification of a virtual device the command is to be performed on;
if an address of the device matches the device address,said device logic latching the data transferred across the data bus and address bus, andstoring the virtual device identification, the type of command and the command data in the virtual device register identified by the virtual device register address;
said device logic performing the command identified by the type of command to be performed on the virtual device identified by the virtual device identification located in the virtual device register using the command data stored in the virtual device register.
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Accused Products
Abstract
A method and apparatus that provides for the atomic transfer of data associated with a command to be transferred to a device consisting of a cache memory which supports a plurality of virtual devices. The atomic transfer enables the device to initiate and complete execution of the command immediately with respect to a particular virtual device without having to wait for data to come during subsequent bus transfers. This insures that the state of the device will be consistent during execution of the command.
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Citations
11 Claims
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1. In a system comprising a CPU, a device that supports a plurality of virtual devices and address bus and data bus each coupled between the CPU and the device, a method for atomically transferring command and data information to the device having device logic comprising the steps of:
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transferring command data across the data bus to the device; transferring address data across the address bus to the device in the same bus cycle with said command data, said address data comprising a device address, an address of a virtual device register, a type of command to be performed and an identification of a virtual device the command is to be performed on; if an address of the device matches the device address, said device logic latching the data transferred across the data bus and address bus, and storing the virtual device identification, the type of command and the command data in the virtual device register identified by the virtual device register address; said device logic performing the command identified by the type of command to be performed on the virtual device identified by the virtual device identification located in the virtual device register using the command data stored in the virtual device register. - View Dependent Claims (2, 3, 4, 5)
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6. A computer system comprising:
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an address bus; a data bus; a central processing unit (CPU) coupled to the address bus and data bus, said CPU causing an command to be performed on a virtual device by transmitting address data across the address bus, said address data comprising a device address, an address of a virtual device register, the type of command to be performed and an identification of the virtual device the command is to be performed on, and command data across the data bus, said command data being transmitted in the same bus cycle with said address data; and a device coupled to the address and data bus, said device supporting a plurality of virtual devices, said device comprising; a virtual device register, receiver circuitry couple to the virtual device register for latching the address data and command data respectively off the address bus and data bus if the device address transmitted across the address bus matches an address of the device, said receiver circuitry further transferring the command data, the type of command and the identification of the virtual device to the virtual device register, and virtual device circuitry coupled to the virtual device register, said virtual device circuitry reading the virtual device register to perform the type of command for the virtual device using the command data stored in the virtual device register. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification