Research-Stack/6-Documentation/docs/x86_64_architecture_specifications.md

x86_64 Architecture Specifications Comparison

Overview

This document catalogs the official x86_64 (AMD64/Intel 64) architecture specifications from both Intel and AMD, and provides a comparison of their implementations.

Official Specification Sources

Intel Specifications

• Intel® 64 and IA-32 Architectures Software Developer's Manual
  • URL: https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html
  • Available as:
    • Combined volume (all 4 volumes in one)
    • Four-volume set
    • Ten-volume set
  • Volume 1: Basic Architecture
  • Volume 2: Instruction Set Reference (A-M)
  • Volume 2: Instruction Set Reference (N-Z)
  • Volume 3: System Programming Guide
  • Volume 4: Model-Specific Registers

AMD Specifications

• AMD64 Architecture Programmer's Manual
  • Combined Volumes 1-5: https://kib.kiev.ua/x86docs/AMD/AMD64/40332-r4.00.pdf (Rev 4.00, April 2020)
  • Volume 1: Application Programming (Pub 24592)
  • Volume 2: System Programming (Pub 24593)
  • Volume 3: General-Purpose and System Instructions (Pub 24594)
  • Volume 4: 128-Bit Media and x87 Floating-Point Instructions (Pub 26568)
  • Volume 5: 64-Bit Media and x87 Floating-Point Instructions (Pub 26569)
• AMD64 Technology Documentation Portal: https://docs.amd.com/

Key Architectural Differences

Origin and Naming

• AMD64: Originally developed by AMD as an extension to x86 architecture
• Intel 64: Intel's implementation of AMD64 (formerly called EM64T)
• Both are binary compatible at the instruction set level

Register Extensions

Both implementations extend the x86 architecture with:

• 64-bit general-purpose registers (RAX, RBX, RCX, RDX, RSI, RDI, RBP, RSP)
• 8 additional 64-bit registers (R8-R15)
• 64-bit instruction pointer (RIP)
• 64-bit flags register (RFLAGS)

Mode of Operation

• Legacy Mode: Runs existing 16-bit and 32-bit x86 applications
• Long Mode:
  • 64-bit mode (native 64-bit operation)
  • Compatibility mode (runs 32-bit protected mode applications)

Memory Addressing

• Virtual Address: 48 bits (current implementations)
• Physical Address: Up to 52 bits (varies by implementation)
• Canonical Addressing: Address bits 48-63 must be sign-extended

Implementation-Specific Features

Intel-Specific Extensions

• Intel Virtualization Technology (Intel VT-x)
• Intel Trusted Execution Technology (TXT)
• Intel SGX (Software Guard Extensions)
• Intel MPX (Memory Protection Extensions)
• Intel TSX (Transactional Synchronization Extensions)

AMD-Specific Extensions

• AMD-V (AMD Virtualization)
• AMD Secure Processor / Platform Security Processor (PSP)
• AMD SME (Secure Memory Encryption)
• AMD SEV (Secure Encrypted Virtualization)
• CLZERO (Cache Line Zero instruction)

Research Stack Status

The research stack does not currently contain local copies of these specification documents. The specifications must be accessed from the official vendor URLs above.

References

• Intel SDM: https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html
• AMD64 Manuals: https://kib.kiev.ua/x86docs/AMD/AMD64/