Intel releases X86S instruction set version 1.2, killing multiple 16-bit and 32-bit features

[zohaibahd]

In a nutshell: Intel has unveiled the latest revision of its pared-down X86S instruction set architecture. Version 1.2 takes the trimming trend further by axing multiple 16-bit and 32-bit features. It continues the chipmaker's promise last year to optimize the x86 architecture.

The X86S is Intel's modernization plan for the venerable x86 lineup that powered PCs for decades. The original x86 architecture emerged in 1978 with the 16-bit 8086 processor. As computing demands grew over the decades, Intel added new capabilities to handle 32-bit and 64-bit computing.

However, all those expansions added complexity and bloat. So in May last year, Intel floated the idea of a streamlined, 64-bit-only version dubbed X86S. The goal is to strip out the obsolete bits for a more optimized chip design.

This new version 1.2 spec makes good on that plan by removing multiple 16-bit and 32-bit features. These include real and protected 16-bit modes, 16-bit addressing, the antiquated ring 1 and 2 privilege levels, and other little-used legacy stuff.

#Intel released the X86S (simplified, legacy-free X86) specification 1.2 with a lot of modifications and new CPUID bits:
CPUID.7.1.ECX[2]: X86S (LEGACY_REDUCED_OS_ISA)
CPUID.7.1.ECX[4]: SIPI64 (64-bit "start-up" interprocessor interrupt)https://t.co/vX9R6hINqt https://t.co/dcekaF540v pic.twitter.com/FCOOz6FKGs

– InstLatX64 (@InstLatX64) September 24, 2024

In its previous blog, Intel claimed that remnants from the 8086 and 386 eras have become unnecessary in our 64-bit world. Though details are murky, a "32-bit compatibility mode" is still present.

Intel also highlighted that for 64-bit operating systems from the late 2000s and early 2010s, Intel is leaning on modern virtualization to provide support. That means anything older, like Windows XP, DOS, or other 16-bit/32-bit relics, would be relegated to virtual machines and emulators from now on.

It is unclear how far Intel will go in the name of efficiency. One of x86's superpowers has always been its unmatched legacy support stretching back decades. That allowed old software and hardware to work long after new standards emerged.

If Intel commits to X86S for future CPUs, it could mark a radical break from that longstanding ethos of maximum compatibility. All this has been a long time coming though, especially as the arguably more efficient Arm architecture gains ground thanks to Apple and Qualcomm.

Of course, Intel's decisions won't happen in a vacuum. Longtime x86 partner and rival AMD will likely have significant input. Team Red's 64-bit extensions (AMD64) for x86 paved the way for modern 64-bit computing after Intel's Itanium efforts fizzled out. If X86S is to succeed, the two chip giants will likely have to coordinate.

Permalink to story:

Intel releases X86S instruction set version 1.2, killing multiple 16-bit and 32-bit features

 

[guillejp]

Wow... I don't quite understand this really, but it sounds like one of those things that go nowhere... I want to understand what it would take for this to have some actual impact, so I'm asking a few questions:

- It would require that intel and AMD release processors with this instruction set and without x86, to completely replace it?
- Isn't that too unrealistic and would leave out much software? Or, it could be started for consumer processors, right?
- But they would also include SSE4.2, AVX2...?
- And Windows 11/12 would need to support this specific instruction set?
- Doesn't the "32 bit compatibility mode" defeat the purpose?
- Isn't this kinda unlikely and pointless?

 

[VitalyT]

The x86 is obsolete now. Intel and AMD both should have abandoned the ancient x86 architecture years ago, and start making 64-bit-only CPU-s. That would also have prompted software vendors to update everything to 64-bit, not drag their feet with 32-bit into today still.

The fact that they both didn't do it is what allowed Apple beat them to it, by making its own CPU-s, free of the legacy instruction sets, and far more efficient.

b.t.w. Intel did produce 64-bit only Itanium between 2001 and 2019. They should have revised the mainstream CPU-s for 64-bit only years ago, and throw away all obsolete instruction sets.

There still multiple instruction sets in the newest CPU-s from both Intel and AMD that nobody needs, like MMX, SSE-s, 3DNow, etc. All of which is just pointless legacy crap now.

 

[HardReset]

- It would require that intel and AMD release processors with this instruction set and without x86, to completely replace it?

That's about how you define "x86". CPU is still x86 but some unused features are cut off. Just like AMD 64 long mode "64-bit mode" does not support 16-bit software.

- Isn't that too unrealistic and would leave out much software? Or, it could be started for consumer processors, right?

Not much modern software. Like said, many old software usually runs on virtual machines anyway. Like DOS or Windows XP.

- But they would also include SSE4.2, AVX2...?

Why not include?

- And Windows 11/12 would need to support this specific instruction set?

Probably no, again, only (almost) unused legacy stuff is cut down.

- Doesn't the "32 bit compatibility mode" defeat the purpose?

No because it Might be much slower than on today's CPUs.

- Isn't this kinda unlikely and pointless?

No. It allows much more efficient CPU design.

The x86 is obsolete now. Intel and AMD both should have abandoned the ancient x86 architecture years ago, and start making 64-bit-only CPU-s. That would also have prompted software vendors to update everything to 64-bit, not drag their feet with 32-bit into today still.

The fact that they both didn't do it is what allowed Apple beat them to it, by making its own CPU-s, free of the legacy instruction sets.

Tell that to Microsoft. Finally, Windows 11 is 64-bit only. Windows 10 had 32-bit version.

How did Apple beat x86 is totally out of my mind.

 

[Theinsanegamer]

The x86 is obsolete now. Intel and AMD both should have abandoned the ancient x86 architecture years ago, and start making 64-bit-only CPU-s. That would also have prompted software vendors to update everything to 64-bit, not drag their feet with 32-bit into today still.

The fact that they both didn't do it is what allowed Apple beat them to it, by making its own CPU-s, free of the legacy instruction sets, and far more efficient.

b.t.w. Intel did produce 64-bit only Itanium between 2001 and 2019. They should have revised the mainstream CPU-s for 64-bit only years ago, and throw away all obsolete instruction sets.

There still multiple instruction sets in the newest CPU-s from both Intel and AMD that nobody needs, like MMX or SSE-s, 3DNow, etc.

Oh professor, why didnt intel listen to YOU?!?

x86 is an instruction set, not just an architecture. That's why its called x86-64, and not just 64. Removing x86 instructions would break most software, not just legacy applications.

The instruction sets make up a TINY portion of the CPU, and their power use is so marginal it doesnt exist.

BTW, did you see that lunar lake is posting better battery life then macbooks? Whoops, guess apple didnt need to remove backwards compatibility after all...

That's about how you define "x86". CPU is still x86 but some unused features are cut off. Just like AMD 64 long mode "64-bit mode" does not support 16-bit software.

Not much modern software. Like said, many old software usually runs on virtual machines anyway. Like DOS or Windows XP.

Why not include?

Probably no, again, only (almost) unused legacy stuff is cut down.

No because it Might be much slower than on today's CPUs.

No. It allows much more efficient CPU design.


Tell that to Microsoft. Finally, Windows 11 is 64-bit only. Windows 10 had 32-bit version.

How did Apple beat x86 is totally out of my mind.

How does this allow more efficient design? You know the x86 portion of CPUs is TINY, right? Less then 1% of the CPU is dedicated to it. How much power do you think it takes?

I'm really surprised AMD isnt hiring all the unemployed engineers here.

Wow... I don't quite understand this really, but it sounds like one of those things that go nowhere... I want to understand what it would take for this to have some actual impact, so I'm asking a few questions:

- It would require that intel and AMD release processors with this instruction set and without x86, to completely replace it?
- Isn't that too unrealistic and would leave out much software? Or, it could be started for consumer processors, right?
- But they would also include SSE4.2, AVX2...?
- And Windows 11/12 would need to support this specific instruction set?
- Doesn't the "32 bit compatibility mode" defeat the purpose?
- Isn't this kinda unlikely and pointless?

Yes, it is ultimately pointless, but it pleases the peanut gallery that demand intel abandon legacy because "Da FuTaH" or something like that.

 

[HardReset]

There still multiple instruction sets in the newest CPU-s from both Intel and AMD that nobody needs, like MMX, SSE-s, 3DNow, etc. All of which is just pointless legacy crap now.

SSE2 is part of x86-64. 3D-NOW! was removed on Bulldozer.

How does this allow more efficient design? You know the x86 portion of CPUs is TINY, right? Less then 1% of the CPU is dedicated to it. How much power do you think it takes?

When I said efficient, I didn't mean only power. Like leaving out 32-bit x87 would allow leaving out also 64-bit x87 and concentrating only SSE2+.

 

[NotYourITguy]

The x86 is obsolete now. Intel and AMD both should have abandoned the ancient x86 architecture years ago, and start making 64-bit-only CPU-s. That would also have prompted software vendors to update everything to 64-bit, not drag their feet with 32-bit into today still.

I think you mean to say you want x86 to be obsolete. x86 is presently the best selling architecture there is and will likely be for several more years until ARM has a shot at the top spot.

 

[Starfals]

If this breaks old apps that I constantly use (even in 2024...) ill be pissed for sure. Hell, im sure it might even break some newer apps. This is unacceptable to me.. The power of PC is usually being able to use stuff from 20-25 years ago TODAY. That's kind of why I hate consoles too, just as a side note. Consoles are stuck in 1 generation, PC is not.

Anything past 2000 should work mostly fine today, as I have tested many many things. The moment this stops happening is the moment I stop buying newer CPUs that don't support everything. In fact, this sounds like a total nightmare to me...

 

[Mr Majestyk]

So people with old apps should drag down everyone to shitty performance levels. Apple bit the bullet and gave everyone a timeline to update to 64 bit only. Windows users have had donkeys years to move on.

 

[bandit8623]

So people with old apps should drag down everyone to shitty performance levels. Apple bit the bullet and gave everyone a timeline to update to 64 bit only. Windows users have had donkeys years to move on.

apple only has its own hardware to support. windows(Microsoft) supports a ridiculous amount.

 

[takaozo]

First HT and now x86, looks like Intel is moving in the right way to get rid of past security issues. Now get rid of AMT and SOL for home users and maybe your CPU's will have a chance at even better security.

 

[RexSceleratorum]

If this breaks old apps that I constantly use (even in 2024...) ill be pissed for sure. Hell, im sure it might even break some newer apps. This is unacceptable to me.. The power of PC is usually being able to use stuff from 20-25 years ago TODAY.

There was an earlier Techspot article about this that was much more informative. The changes will affect mostly operating systems, not application software, given continued support for 32-bit compatibility. Real mode 16-bit or earlier will have to be virtualized, which is effortless in modern hardware.

The changes mostly affect boot up, so operating systems will require new and radically simplified bootstrapping that will no longer give headaches to computer science students.

Microsoft will immediately release an x86s Windows flavor, and various Linux distros will follow suit. You're only in trouble if you want to use unsupported legacy operating systems bare metal (XP, Win7, old Linux versions). You will have to resort to virtualization.

 

[Biostud]

When Apple moved from x86 to arm they made Rosetta. Can't Microsoft/Intel just do something similar that will make legacy software compatible with x86S? And wouldn't it be easier than a x86 to arm transition?

 

[fadingfool]

When Apple moved from x86 to arm they made Rosetta. Can't Microsoft/Intel just do something similar that will make legacy software compatible with x86S? And wouldn't it be easier than a x86 to arm transition?

[cough] Rosetta 2[/cough]
Rosetta was for the move to x86 from powerpc

 

[noblody]

If this breaks old apps that I constantly use (even in 2024...) ill be pissed for sure. Hell, im sure it might even break some newer apps. This is unacceptable to me.. The power of PC is usually being able to use stuff from 20-25 years ago TODAY. That's kind of why I hate consoles too, just as a side note. Consoles are stuck in 1 generation, PC is not.

Anything past 2000 should work mostly fine today, as I have tested many many things. The moment this stops happening is the moment I stop buying newer CPUs that don't support everything. In fact, this sounds like a total nightmare to me...

You can run almost seamlessly linux inside windows. You can run android apps. I see no reason for older apps not to run in a virtual 32bit machine without you even noticing.

 

[BadThad]

"That means anything older, like Windows XP, DOS, or other 16-bit/32-bit relics, would be relegated to virtual machines and emulators from now on."

That's how you keep backwards compatibility.