Processor Boot Configuration via NVM and Golden Signature

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Solution Overview

Problem

Existing processor and controller boot methods either expend valuable pins or fail to secure the boot process from unauthorized access, as they do not allow users to disable specific boot options or choose alternate methods without using additional pins.

Innovation Solution

The solution involves a method where the boot options are defined in two stages: initially using factory-defined hardware pins for booting an un-programmed device, and subsequently allowing users to program user-defined boot options into on-chip NVM, enabling flexible selection of boot methods without requiring dedicated pins, and ensuring secure boot processes by validating user-defined configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If log2(n) pins are provided to allow selection between n boot options, then boot method selection flexibility is improved, but pin consumption increases

Engineering Contradiction:

Improveboot method selection flexibilityVSAvoidpin consumption

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The system performs preliminary action by checking for a golden signature in external memory before attempting to boot from it. This preliminary check allows the system to determine boot method in advance without consuming additional pins during operation, resolving the contradiction between boot flexibility and pin consumption

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism - a golden signature check - that mediates between the boot selection requirement and pin availability. The CPU acts as an intermediary by listening to communication peripheral ports for the golden signature, enabling boot method selection without dedicated selection pins

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If all communication peripherals are always enabled to reduce boot pins, then pin consumption is reduced, but security deteriorates due to unauthorized access risk

Engineering Contradiction:

Improvepin consumptionVSAvoidboot process security

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The system applies preliminary anti-action by checking for a golden signature before allowing boot from external memory. This preliminary security check prevents unauthorized users from downloading spoof applications, countering the security risk that would otherwise exist when peripherals are always enabled

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system implements feedback by having the CPU listen for a golden signature on communication peripheral ports. This feedback mechanism allows the system to detect whether external memory contains authorized boot code, enabling secure boot operation without disabling peripherals

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If users are allowed to program boot method into on-chip NVM, then boot method customization is improved, but the ability to eliminate boot pins is limited

Engineering Contradiction:

Improveboot method customizationVSAvoidboot pin availability

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10459735B2Scalable boot options for a processor/controller

Publication Date: 2019.10.29 TEXAS INSTRUMENTS INC

AI summary

An integrated circuit (IC) chip and method of booting the IC are disclosed. The method includes determining whether a boot pin configuration has been programmed and responsive to determining that the boot pin configuration has been programmed, performing a boot method indicated in a user-defined boot table. Responsive to determining that the boot pin configuration key has not been programmed, the method performs a boot method selected from a factory-defined boot table.