Processor Boot ROM Bridging 16-bit Legacy and 64-bit Paged Modes
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Solution Overview
Problem
Newer computer processors operating in 64-bit paged mode struggle to support the older 16-bit real mode boot process, making it difficult to maintain compatibility and efficiency in booting processes.
Innovation Solution
The implementation of a hardware processor architecture with sliced memory circuitry, including L0 and L1 memory levels, page miss handlers, and prefetchers, allows for efficient transition between different addressing modes by managing memory operations and page translations effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If newer processors operate in 64-bit paged mode, then processing power and memory management capability are improved, but compatibility with older 16-bit real mode boot process deteriorates
Solution Approach 1:
The patent introduces a boot ROM (Read-Only Memory) as an intermediary component that bridges the gap between 64-bit processors and 16-bit boot processes. The boot ROM contains legacy 16-bit boot code that can execute the traditional real mode boot sequence, then transition to 64-bit mode. This mediator allows newer processors to maintain compatibility with older boot processes without compromising their advanced 64-bit capabilities.
Solution Approach 2:
The system dynamically switches between different operating modes during the boot process. Initially, the processor operates in 16-bit real mode to execute legacy boot code from the boot ROM, then dynamically transitions to 64-bit paged mode for normal operation. This dynamic mode switching enables the processor to adapt its architecture to match the requirements of different boot stages and operating conditions.
2Adaptability or versatility
If legacy 16-bit real mode boot process is supported, then backward compatibility is improved, but boot process complexity and difficulty of implementation deteriorates
Solution Approach 1:
The boot process is segmented into distinct stages: first stage boot code in the boot ROM handles 16-bit real mode initialization, then transitions to second stage boot code that operates in 64-bit mode. This segmentation separates the legacy compatibility requirements from the modern processing requirements, making the overall system easier to implement and maintain by isolating the complexity into manageable, independent segments.
Solution Approach 2:
The boot ROM serves as an intermediary that encapsulates all the complexity of 16-bit real mode boot processing. By placing the legacy boot code in a dedicated ROM component rather than attempting to integrate it into the main processor logic, the complexity is isolated to a separate module, simplifying the overall system design and making backward compatibility easier to maintain.
3Quantity of substance
If memory addressing transitions from 16-bit segmented model to 64-bit paged model, then memory capacity and management efficiency are improved, but support for traditional boot processes deteriorates
Solution Approach 1:
The memory addressing mode dynamically changes during the boot process. In the initial stage, the system uses 16-bit segmented addressing to support legacy boot code execution, then dynamically transitions to 64-bit paged addressing for the operating system and applications. This dynamic adaptation allows the system to provide full memory capacity and efficient management while maintaining support for traditional boot processes.
Solution Approach 2:
The system performs preliminary action by establishing 16-bit segmented memory addressing before executing the boot code, then transitions to 64-bit paged mode after the boot process is complete. This preliminary setup ensures that the memory subsystem is properly configured for legacy compatibility before the more demanding 64-bit operations begin, resolving the conflict between memory capacity and boot process support.
Data Source
AI summary
An apparatus and method for booting a processor directly into a paged 64-bit execution environment. For example, one embodiment of an a processor comprises: a register to store a first value and a second value related to a secure boot process; a plurality of cores, at least one of which performs operations comprising: receiving a first initialization message, the core to clear a plurality of registers responsively; receiving a second initialization message and reading the first and second values responsively, the first value indicating whether a first initialization mode is supported, and the second value comprising an address pointer identifying a data structure comprising a plurality of state values; and initializing a paged 64-bit execution environment using the state values from the data structure responsive to the first value indicating the first initialization mode is supported and the data structure indicating enabling the paged 64-bit execution environment.