Hewlett-Packard Company

Hewlett-Packard Development Company, L.p.

Other

Leith L Johnson

Eric M Rentschler

Jeffrey G Hargis

Russell C Brockmann

William S Jaffe

Richard Lawrence Carlson

Jonathan Kent Ross

Russ William Herrell

Larry Jay Thayer

John A Morrison

David Allen Fotland

Andrew Ray Wheeler

Stephen R Undy

Erin Antony Handgen

Daniel V Zilavy

Curtis R McAllister

Gerald J Kaufman, Jr

Matthew B Lovell

Joe Perry Cowan

George Thomas Letey

Chris M Giles

Michael H Cogdill

Matthew B Hewlett-Packard Company Lovell

A system and method for achieving one or more protected regions within a computer system having multiple partitions are disclosed. In at least some embodiments, the system includes an intermediary device for use within the computer system having the multiple partitions. The intermediary device includes a fabric device, and a first firewall device capable of limiting communication of a signal based upon at least one of a source of the signal and an intended destination of the signal, the first firewall device being at least indirectly coupled to the fabric device. The intermediary device further includes a first conversion device that is one of integrated with the first firewall device and distinct from the first firewall device, and that is capable of converting between a processor address and a fabric address for use by the fabric device. In some embodiments, the various devices each include Control and Status Registers (CSRs).

System and method for achieving protected region within computer system

In one embodiment, a memory control system is provided with a memory controller having 1) a first interface to receive memory read/write requests; 2) a second interface to read/write data from a number of memory modules; 3) a memory cache containing spare memory locations; and 4) logic to, upon receipt of a memory read/write request, i) direct the read/write request to the memory cache when an address associated with the read/write request resides in the memory cache, and ii) direct the read/write request to the second interface when the address associated with the read/write request does not reside in the memory cache.

Memory controller

A directory cache is provided with a plurality of directory entries configured to store information regarding copies of memory lines stored in a plurality of caches. The entries are divided into sets of N entries, with each set of N entries being addressable via an index. The directory cache is also provided with a cache controller. The cache controller retrieves a set of N entries associated with an index corresponding to a memory line, and if a tag portion of one of the retrieved entries corresponds to the memory line, the cache controller determines whether the one of the retrieved entries contains an indication that information regarding the memory line is stored in at least a second one of the retrieved entries.

Directory caches, and methods for operation thereof

Method and apparatus for allowing a direct memory access unit to have access to a virtual address space is accomplished by receiving a request for memory access from the direct memory access device; determining a device identifier according to the received request for memory access; determining a memory protection schema according to the determined device identifier; and granting the direct memory access unit access to memory in accordance with the determined memory protection schema.

Method and apparatus for direct input and output in a virtual machine environment containing a guest operating system

A double data rate memory controller is provided with a plurality of data and strobe pads, means for receiving data and strobe signals via said pads at 1&#xd7; double data rate memory speed, and means for receiving data and strobe signals via said pads at M&#xd7; double data rate memory speed (M&#x2267;2).

Memory controller driver circuitry having a multiplexing stage to provide data to at least N-1 of N data propagation circuits, and having output merging circuitry to alternately couple the N data propagation circuits to a data pad to generate either a 1x or Mx stream of data

A double data rate memory controller is provided with a plurality of data and strobe pads, means for receiving data and strobe signals via said pads at 1x double data rate memory speed, and means for receiving data and strobe signals via said pads at Mx double data rate memory speed (M2).

Memory controller having receiver circuitry capable of alternately generating one or more data streams as data is received at a data pad, in response to counts of strobe edges received at a strobe pad

Methods and apparatus are disclosed herein for providing tri-state noise immunity for memory systems such as DDR memory systems, wherein 1) there are large variations in read data loop delay, and 2) strobe buses have similar termination and threshold voltages. In one embodiment, strobe receiver circuitry includes a counter and counter control logic. The counter updates a count in response to strobe edges of received strobe signals. The counter control logic enables the counter before each strobe signal is received by generating control signals asynchronously with respect to the received strobe signals. The counter control logic also resets the counter after each strobe signal is received by receiving feedback from the counter and, in response to the feedback, resetting the counter asynchronously with respect to the received strobe signals. The strobe receiver circuitry may form part of a DDR memory controller.

Memory controller receiver circuitry with tri-state noise immunity

A module array includes a lead-in transmission line from a driving source. The lead-in transmission line ends with a series impedance between the lead-in transmission line and a star node. The star node has a terminating impedance between it and a termination voltage. At least two branch transmission lines diverge from the star node. Modules connect to the branch transmission lines in a comb topology.

Module array

Methods and apparatus for writing data to memory are disclosed herein. In general, the methods and apparatus provide a memory controller with means for writing data at different rates. Data may need to be written to memory at different rates because, for example, the memory controller is used in environments where it attaches directly to a number of memory modules, and/or in environments where it attaches to a number of memory modules via an intermediary chip. The intermediary chip may, for example, comprise demultiplexers which receive data from the memory controller at twice the rate which data could be written directly to a memory module. The intermediary chip may then simultaneously transmit the demultiplexed write data to memory modules in two or more banks of memory modules.

Memory controller with 1X/MX write capability

Methods and apparatus for receiving data from memory, the data being associated with a strobe, are disclosed herein. In general, the methods and apparatus provide a memory controller with a means for receiving data at different rates. Data may be received by a memory controller at different rates because, for example, the memory controller is used in environments where it attaches directly to a number of memory modules, and/or in environments where it attaches to a number of memory modules via an intermediary chip. The intermediary chip may, for example, include multiplexers which receive data from two or more banks of memory modules and then multiplex the data into one or more data streams which are then transmitted to the memory controller at twice the rate which the memory modules in either bank could transmit data to the memory controller.

Memory controller with 1&times;/M&times; read capability

A memory controller and method for intermittently providing a clock signal to a synchronous memory. While no transactions are occurring, a clock signal is held in an idle state. Upon the start of a transaction with the synchronous memory, the clock signal is activated. When activated, the clock signal functions as a periodic timing reference clock. The clock signal remains active during the transaction. Upon completion of the transaction, the clock signal returns to the idle state. In one embodiment, a finite state machine utilizes a counter to control the process. Upon the start of a transaction with the synchronous memory a new count is loaded in a counter. The value for the new count depends, for example, on the number of commands necessary to complete the transaction. The counter, beginning with the new count, regularly increments. When the counter reaches a maximum value, the clock signal returns to the idle state. The clock signal remains in the idle state until the start of a second transaction with the synchronous memory. Then, again the clock signal is activated. The clock signal remains active during the second transaction. Upon completion of the second transaction, the clock signal is again returned to the idle state.

Memory controller and method for intermittently activating and idling a

A memory controller and at least one memory module exchange data at high transfer rates by minimizing clock skew. When writing data to the memory module, the memory controller generates a clock signal that travels along a first clock line segment. The data bus carries the write data, and the electrical characteristics of the data bus and first clock line segment are matched such that incident wavefronts of the data bus and clock signal arrive at the memory module in fixed relation to one another. When reading data, the first clock line segment is looped back from the memory module to the memory controller along a second clock line segment, with a copy of the clock signal provided on the second clock line segment. The data bus carries the read data, and the electrical characteristics of the data bus and the first clock line segment are matched such that incident wavefronts of the data bus and clock signal arrive at the memory controller in fixed relationship to one another. The present invention provides a substantial increase in memory bandwidth with minimal design changes to prior art memory systems.

Method and apparatus for generating and distributing clock signals with

Disclosed herein are methods and apparatus which provide a processor with raw, uncorrected data. The uncorrected data (or pre-corrected data) is retrieved from memory and then 'bypassed' to a processing unit before its error status is known. Concurrently, error correction hardware determines the data's error status. Since the correct/incorrect indication is the first result available from error correction hardware, this result may be used to gate the actions of a processing unit prior to its taking an irrevocable action with possibly incorrect data. If bypassed data is incorrect, processing unit control logic may flag it as such and read corrected data from the output of error correction hardware. If bypassed data is correct (as will usually be the case), bypassed data may be consumed by a processing unit in due course.

Opportunistic use of pre-corrected data to improve processor performance

A PC bus architecture that is compatible with an industry standard bus architecture and allows devices to transfer data more effeciently. The protocol of the present invention allows a data transaction in which a data transfer request can be made by a bus master device and then queued so that the transaction occurs at a later time allowing the bus to be free for other transactions until the responding device has prepared the data.

Method for enhanced peripheral component interconnect bus split data

A plurality of MOSFET switches, one per bus line, are used to solve the problem of interfacing between two incompatible devices via a single shared bus. The MOSFET switches used are simple, inexpensive, and very fast. The switches perform two primary functions: 1) isolation of two bus sections (possibly for loading reasons); and 2) translation of incompatible voltages transmitted over the bus.

Growing community of inventors

Fort Collins, CO, United States of America

Leith L Johnson