Electrical computers and digital processing systems: support – Digital data processing system initialization or configuration – Loading initialization program
Reexamination Certificate
2000-01-25
2004-07-20
Lee, Thomas (Department: 2116)
Electrical computers and digital processing systems: support
Digital data processing system initialization or configuration
Loading initialization program
C713S001000, C713S002000, C713S100000, C712S234000, C712S235000, C712S236000, C711S006000, C711S119000, C711S120000, C711S121000, C711S122000, C711S137000, C711S154000
Reexamination Certificate
active
06766447
ABSTRACT:
TECHNICAL FIELD
The following description relates to microprocessors, and more particularly to microprocessors that use speculative reading.
BACKGROUND
Many of today's microprocessors, notably Pentium processors, use processing techniques collectively referred to as “dynamic execution” techniques. These techniques are associated with multistage execution (“pipelining”) and are designed to increase processing speed by eliminating wasted instruction loading resulting from branching. The various techniques include branch prediction and speculative reading and execution.
Branch prediction is the capability of the processor to predict which branch of a conditional jump or loop the processor will take. As a result of branch prediction, the processor guesses which instructions to read ahead and load into the pipeline. Because the processor is guessing at what instructions to read ahead, this technique is called “speculative execution.”
SUMMARY
It is recognized that processors that use dynamic execution techniques may cause problems during initialization of random access memory. It is further recognized these problems are associated with the computer code that implements the initialization, which has one or more branches that cause the processor to perform speculative reading. The following description presents several examples of branches that occur within the BIOS code and that may lead to initialization failures due to speculative reading.
Solutions to the memory initialization problem involve identifying processors and code that can cause problems. If a source (or a potential source) of the problem is discovered, steps can be taken to prevent speculative reading during the initialization.
An advantage of the above-described process is that a potential problem that can occur with certain processors during memory initialization is both detected and prevented from occurring. In the absence of the herein-described relationship between speculative reading and memory initialization, memory initialization failures could occur and not be easily diagnosed.
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Jue Stephen D.
Mendelow Matthew B.
Baker & Botts L.L.P.
Dell Products L.P.
Patel Nitin
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