Intel released a whitepaper this week in which it offers something unusual. The document examines the possibility of abandoning the 16- and 32-bit architectures and going fully to 64-bit, which would drop support for older software. Instead, the OEM offers a new “Intel x86-S” architecture that would only support 64-bit. To justify this choice, Intel stated that it would simplify both hardware and software, but did not specify whether this would result in performance or efficiency gains for end users. The document lists several potential benefits of a 64-bit architecture.
The first 16-bit processors came out in the 1970s. Examples include the five-chip National Semiconductor IMP-16 (1973), the two-chip NEC μCOM-16 (1974), and the three-chip Western Digital MCP-1600 (1975), and the five-chip Toshiba T-3412 (1976). And although 32-bit processors were already being used in mainframe computers in the 1960s, the migration of personal computers from 16 to 32 bits began in the 1980s. They were built in 16-bit mode to ensure compatibility with 16-bit applications.
A tech note published on the Intel Developer Blog proposes a fairly radical change to the x86-64 architecture: a new x86S architecture that will simplify the design of future processors and a computer’s boot process by removing 16-bit support and more 32-bit hardware support. The result would be a family of processors that boot directly in x86-64 mode. According to Intel, this would bypass the traditional series of transitions including: from 16-bit real mode to 32-bit protected mode and then to 64-bit long mode; or from 16-bit mode directly to 64-bit mode.
Today’s chips must go through these steps at system startup. Intel writes: A 64-bit architecture removes some older architectural appendages, thereby reducing the overall complexity of the software and hardware architecture. Further changes could be made in line with modern software delivery by exploring a pure 64-bit mode architecture. This includes the following changes:
- Using the simplified 64-bit segmentation model to support 32-bit application segmentation, consistent with what modern operating systems already use;
- Removed rings 1 and 2 (not used by modern software) and deprecated segmentation functions like gates.
- remove support for 16-bit addressing;
- Removed support for Ring 3 I/O port access;
- Eliminate chained I/O ports that supported a legacy CPU-driven I/O model.
- Limiting the use of the X2APIC local interrupt controller (APIC) and removing support for 8259;
- Removed some unused operating system mode bits.
The long lifespan of the Intel architecture has resulted in a rich software ecosystem with an installed base standard ranging from PC to cloud, mobile and embedded devices to supercomputers and beyond. Since its introduction over 20 years ago, the Intel 64 architecture has become the dominant operating mode. For i, Microsoft has stopped shipping the 32-bit version of its Windows 11 operating system. Intel firmware no longer natively supports non-UEFI64 operating systems. 64-bit operating systems are the de facto standard today, says Intel.
The US OEM adds: 64-bit operating systems retain the ability to run 32-bit applications, but no longer natively support 16-bit applications. Intel believes this development offers opportunities to simplify our hardware and software ecosystem. Some legacy modes have little use in modern operating systems other than starting the CPU in 64-bit mode. In addition, the developer notice is accompanied by a 46-page technical white paper [PDF] It details the exact changes Intel is considering.
According to Intel, keeping legacy hardware requirements can have serious implications for a device’s microarchitecture and design. For example, startup and code execution improvements cannot be considered if they negatively impact backwards compatibility. Devices that require backwards compatibility must provide space for older hardware, space that could be better used by newer hardware accelerators and runtimes. Backward compatibility could also have broader implications for the hardware used in modern designs.
In addition, Intel adds that maintaining compatibility with previous versions can also allow security vulnerabilities to persist in newer designs. This is especially true during the boot process, where older systems may not apply strict security measures and allow malicious code to run. Finally, according to the company, the switch will not completely remove support for older operating systems. As the company points out in its post, Intel has developed virtualization techniques that could still allow older software to boot.
Since the company hasn’t said anything about the performance gains that could result from such a change, it’s unclear if most users will be happy with the change, or if it’s just a seamless change that most of us are unlikely to see will notice. Additionally, it’s also possible that this change will never happen, as continued support for the PC ecosystem is a key part of its appeal, and Intel doesn’t want to risk disrupting the status quo even if it did. It’s been over 20 years since 64-bit processors hit the market.
This announcement comes a few months after Intel announced the death of the Pentium and Celeron processors. The company has announced that it will replace those two chips with a single Intel processor starting in 2023. According to Intel, this should make it easier for consumers who want to buy cheap laptops. Intel introduces a new processor for the essential products section: Intel Processor. This new offering will replace the Intel Pentium and Intel Celeron brands in the 2023 laptop product portfolio, Intel said in a blog post published on September 16, 2022.
Source: Intel
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