Intel proposes x86S, a 64-bit only architecture

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Intel publishes a white paper on x86S, a 64-bit only architecture

Intel is paving the way for a transition that removes legacy 32-bit and 16-bit support. 



Most gamers have probably switched to 64-bit architecture years ago because 32-bit OS didn’t support more than 4GB of memory. Modern software, such as the Windows 11 operating system, no longer supports 32-bit CPU architectures either. However, the hardware may still offer legacy support for older systems.

Intel sees an opportunity in removing of the legacy 32-bit and 16-bit mode supports, and they propose a 64-bit only architecture. The company has suggested something called “x86S” which is an architecture design that removes the unnecessary legacy modes and should lead to faster systems in the future.

One of the key benefits of x86S architecture would be a faster booting of the CPU, as there would be no need to use unpaged legacy mode during boot. A transition to x64 architecture only eliminates ‘several stages of trampoline code to enter 64-bit operation’.

Benefits of x64-bit only architecture according to Intel:

• Using the simplified segmentation model of 64-bit for segmentation support for 32-bit applications, matching what modern operating systems already use.
  
• Removing ring 1 and 2 (which are unused by modern software) and obsolete segmentation features like gates.
  
• Removing 16-bit addressing support.
  
• Eliminating support for ring 3 I/O port accesses.
  
• Eliminating string port I/O, which supported an obsolete CPU-driven I/O model.
  
• Limiting local interrupt controller (APIC) use to X2APIC and remove legacy 8259 support.
  
• Removing some unused operating system mode bits.
  

Such a transition would not outright remove legacy operating system support. As the company states in a post, Intel has matured virtualization techniques that could still allow booting of legacy software. How would this work is detailed in a whitepaper (PDF).
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