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Intel Publishes "X86-S" Specification For 64-bit Only Architecture
Intel quietly released a new whitepaper and specification for their proposal on "X86-S" as a 64-bit only x86 architecture. If their plans workout, in the years ahead we could see a revised 64-bit only x86 architecture.
Entitled "Envisioning a Simplified Intel Architecture", Intel engineers lay the case for a 64-bit mode-only architecture. Intel is still said to be investigating the 64-bit mode-only architecture that they also refer to as "x86S". Intel is hoping to solicit industry feedback while they continue to explore a 64-bit mode only ISA.
[...] Under this proposal, those wanting to run legacy 32-bit operating systems would have to rely on virtualization. To further clarify, 32-bit x86 user-space software would continue to work on modern 64-bit operating systems with X86-S.
Also at Tom's Hardware.
(Score: 2, Interesting) by pTamok on Monday May 22, @01:41PM (2 children)
Does this mean that they are also proposing no longer starting a boot in 16-bit real mode? That is, it's 64-bit all the way?
AFAIK all Intel x86 processors start (execute Platform Initialization) in 16-bit real mode, including UEFI-only systems. There's some funky stuff that happens with handover from the Management Engine to the main processor right at the beginning of boot/power on.
https://stackoverflow.com/questions/58651734/do-modern-computers-boot-in-real-mode-or-virtual-real-mode [stackoverflow.com]
https://wiki.osdev.org/Real_Mode [osdev.org]
https://hackaday.com/2017/10/23/write-your-own-x86-bootloader/ [hackaday.com]
(Score: 2) by Immerman on Tuesday May 23, @02:07PM (1 child)
That's how I read the article. Sounds like they'll still (possibly? Not 100% clear.) have native support for 32 bit instructions, the proposal is simply to eliminate all the pre-64-bit modes from the boot sequence.
Which seems reasonable to me - trimming away such long-obsolete support is a necessary part of architecture maintenance. Vanishingly few people still run 16-bit, or even 32-bit OSes, and most of those do so on either native hardware or within emulators.
Of course, I assume modern OSes would have to be modified to recognize the new hardware and not try to jump through a bunch of nonexistent hoops when booting... but I suspect most 64-bit OSes are still actively supported, and it should be a pretty minor update. So an excellent time to trim away such deadwood.
(Score: 1) by pTamok on Tuesday May 23, @02:31PM
We'd need to see the deep technical details.
I suspect that, at the very least, the startup would have to be in real mode, for security reasons, to pick up the handover from the Management Engine, unless the ME gets some expanded capabilities which become difficult to audit. So the startup could be in real 64-bit mode, which has its own challenges. From a security point-of-view, there are benefits to starting off with a simple processor in a constrained (read 'well defined') environment, and building up from that. The more complicated the startup configuration (both software and hardware), the more room for bugs, vulnerabilities, and architectural oopsies.