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Intel has tried to move away from x86 three times already. They only stuck with it in the early 2000s because AMD64 forced their hand. This chip shows why Inte

by hajile 4y ago

Intel has tried to move away from x86 three times already. They only stuck with it in the early 2000s because AMD64 forced their hand. This chip shows why Intel would like RISC-V. The core ISA is RISC-V, but every other piece of the chip is proprietary and patented Intel stuff. They are far ahead of almost everyone in these areas, so they don't have much to fear in their current markets from the ISA itself. Few companies have the ability, desire, or connections to spend billions designing a next-gen chip. China has thoroughly proved this. They have designed for x86, Alpha, MIPS, ARM, RISC-V, etc, but none of their designs were particularly good. For example, they recently released their Phytium D2000 chip. It was basically a clone of A72 with improvements, but chips and cheese analysis[0] showed that the supposed improvements actually resulted in a worse design. If designing a good high-performance chip was down to just ISA, then everyone would be doing it. Meanwhile, x86 patents for SSE2 and before have expired (with SSE3 expiring in 2023-4). Analysis of real-world code shows that only a couple percent use something beyond SSE3 and pretty much all of that has fallbacks for SSE2. There's already not much left to keep companies from designing x86-compatible chips (Apple's Rosetta x86 compatibility tracks this expiration exactly). At the same time, x86 is incapable of competing in MCU and DSP markets and Intel's phone offerings were flatly rejected and only competitive when they had the huge advantage of being a couple fabrication nodes ahead of their competitors. Intel paid billions trying to make it happen, but never had many sales outside of the lemonade they made in the embedded market. Intel and AMD would far rather have a non-proprietary solution like RISC-V win than a proprietary one like ARM. [0] https://chipsandcheese.com/2022/09/29/chinas-phytium-d2000-building-on-a72/ https://chipsandcheese.com/2022/09/29/chinas-phytium-d2000-b...

temac 4y ago
> Intel has tried to move away from x86 three times already Also, they tried to move to other ISAs they owned. Trying to move from their position to 3rd party or open ISAs would make even less sense.
- panick21_ 4y ago
  Exactly what I wanted to say. Intel doesn't want x86, it wants something better day control. They use RISC-V to compete in markets other then where x86 is dominant. That seems pretty clear.
- hajile 4y ago
  ISAs have become a commodity. The important x86 patents are all expiring. Nothing would prevent a third party from recreating AVX using different instruction designs that would avoid those patents too. The non-commodity stuff is all the interconnects, memory controllers, caches, etc. Having access to the Athlon XP or Pentium 4 cache, interconnect, or MC designs simply doesn't matter. Intel has these bits locked down already. As the ISA is commodity, the only parts that matter are efficiency, compatibility, extensibility, and cost. RISC-V allows them to penetrate new markets where x86 either can't compete or people don't believe it could compete because it is much more efficient at the low end. On the high-end, simplifying stuff in one area means you have the ability to increase the complexity and performance somewhere else. On the compatibility front, Apple has already forced their hand by being compatible enough to offer a path to ARM. x86 is not so extensible at this point. Lots of the best instruction encodings are wasted on stuff like BCD and even x86_64 has lots of legacy and extensibility issues. RISC-V not only solves this problem, but Intel is big enough to exert a lot of pressure on future standards. Cost is a problem that isn't to be underestimated. ARM charges 1-3% per chip. That's something like 8-10% of gross margins. RISC-V means Intel can get a new ISA that is already being picked up by everyone (rather than spending billions on forcing a new one only to fail as they've already done). In short, there are a lot of advantages and very few downsides to Intel making the switch.
monocasa 4y ago
I think the real reason is they're thinking about opening their foundry to external customers in a meaningful way. A modern foundry is expected to have a suite of hard IP blocks to drop on a design to cover PPA sensitive blocks like CPUs someone would want, and blocks with analog bits like PHYs. Best way to ameliorate people's concerns is to have shipped a chip that runs with those blocks.
sbf501 4y ago
I wouldn't say "move away", I would say "augment their product line". What are the three? I can only think of two: IA64 and i960, but those weren't departures. I worked on Itanium (and McKinely, and Madison). They were never intended for desktops. (In fact, back then there was still this notion of Desktop and Workstation, which is essentially dead today.) The i960 was a fantastic CPU and I only know the wikipedia version of what happened to it, since it was before my time (well, they were producing it when I worked there, but I was ignorant of the climate). However, it was never a "move away from x86" product, it had great # of embedded customers. Again, never for desktops.
- klelatti 4y ago
  Probably iAPX 432 would be the third.
  - sbf501 4y ago
    According to wikipedia this was before x86, so I don't think they were trying to "move away from x86" with this, since x86 didn't exist yet.
    - klelatti 4y ago
      Fair comment. I think it's fair to say though it was intended to be a move away from the main PC microprocessor line (which you can argue traced a path through 8080 to 8086 and beyond ) and ultimately replace it at the high end - so in spirit similar to Itanium even if not an 'x86 replacement'.
    - hajile 4y ago
      x86 traces it's DNA all the way back to the 8008 which led to the extended 8080 which led to the backward compatible 8085 then 8086 and the x86 architecture. 8008 was almost a full decade before the launch of the iAPX 432. The roots of x86 were in one of the first major ISAs ever created (and something like the 2nd or 3rd microprocessor architecture) which is pretty remarkable when you think about it.
toast0 4y ago
> Intel's phone offerings were flatly rejected and only competitive when they had the huge advantage of being a couple fabrication nodes ahead of their competitors. I think there was a good amount of ecosystem issues there. Android x86 phones shipped and were ok, but too many apps shipped native code without an x86 flavor; I don't remember if Google had per-arch builds on Play Store yet, but those also cause issues because people pull those builds and host them on apkg sites, then users have problems when installing them on wrong arch phones. Intel canceled the atom for phones lines days before Microsoft demoed Continuum, which would have been an obvious outlet for an x86 phone. Of course, Microsoft threw in the towel on WM10 before launch too, so maybe Intel wasn't willing to stick it out because they saw Microsoft was going to mess it up. In an alternate reality, the Lumia 950 would be a phone in your pocket and an x86 desktop running real apps on your desk, instead of stuck running app store apps and (pre-chromium) Edge only.

by hajile 4y ago

temac 4y ago

> Intel has tried to move away from x86 three times already Also, they tried to move to other ISAs they owned. Trying to move from their position to 3rd party or open ISAs would make even less sense.

panick21_ 4y ago
Exactly what I wanted to say. Intel doesn't want x86, it wants something better day control. They use RISC-V to compete in markets other then where x86 is dominant. That seems pretty clear.
hajile 4y ago
ISAs have become a commodity. The important x86 patents are all expiring. Nothing would prevent a third party from recreating AVX using different instruction designs that would avoid those patents too. The non-commodity stuff is all the interconnects, memory controllers, caches, etc. Having access to the Athlon XP or Pentium 4 cache, interconnect, or MC designs simply doesn't matter. Intel has these bits locked down already. As the ISA is commodity, the only parts that matter are efficiency, compatibility, extensibility, and cost. RISC-V allows them to penetrate new markets where x86 either can't compete or people don't believe it could compete because it is much more efficient at the low end. On the high-end, simplifying stuff in one area means you have the ability to increase the complexity and performance somewhere else. On the compatibility front, Apple has already forced their hand by being compatible enough to offer a path to ARM. x86 is not so extensible at this point. Lots of the best instruction encodings are wasted on stuff like BCD and even x86_64 has lots of legacy and extensibility issues. RISC-V not only solves this problem, but Intel is big enough to exert a lot of pressure on future standards. Cost is a problem that isn't to be underestimated. ARM charges 1-3% per chip. That's something like 8-10% of gross margins. RISC-V means Intel can get a new ISA that is already being picked up by everyone (rather than spending billions on forcing a new one only to fail as they've already done). In short, there are a lot of advantages and very few downsides to Intel making the switch.

monocasa 4y ago

I think the real reason is they're thinking about opening their foundry to external customers in a meaningful way. A modern foundry is expected to have a suite of hard IP blocks to drop on a design to cover PPA sensitive blocks like CPUs someone would want, and blocks with analog bits like PHYs. Best way to ameliorate people's concerns is to have shipped a chip that runs with those blocks.

sbf501 4y ago

I wouldn't say "move away", I would say "augment their product line". What are the three? I can only think of two: IA64 and i960, but those weren't departures. I worked on Itanium (and McKinely, and Madison). They were never intended for desktops. (In fact, back then there was still this notion of Desktop and Workstation, which is essentially dead today.) The i960 was a fantastic CPU and I only know the wikipedia version of what happened to it, since it was before my time (well, they were producing it when I worked there, but I was ignorant of the climate). However, it was never a "move away from x86" product, it had great # of embedded customers. Again, never for desktops.

klelatti 4y ago
Probably iAPX 432 would be the third.
- sbf501 4y ago
  According to wikipedia this was before x86, so I don't think they were trying to "move away from x86" with this, since x86 didn't exist yet.
  - klelatti 4y ago
    Fair comment. I think it's fair to say though it was intended to be a move away from the main PC microprocessor line (which you can argue traced a path through 8080 to 8086 and beyond ) and ultimately replace it at the high end - so in spirit similar to Itanium even if not an 'x86 replacement'.
  - hajile 4y ago
    x86 traces it's DNA all the way back to the 8008 which led to the extended 8080 which led to the backward compatible 8085 then 8086 and the x86 architecture. 8008 was almost a full decade before the launch of the iAPX 432. The roots of x86 were in one of the first major ISAs ever created (and something like the 2nd or 3rd microprocessor architecture) which is pretty remarkable when you think about it.

toast0 4y ago

> Intel's phone offerings were flatly rejected and only competitive when they had the huge advantage of being a couple fabrication nodes ahead of their competitors. I think there was a good amount of ecosystem issues there. Android x86 phones shipped and were ok, but too many apps shipped native code without an x86 flavor; I don't remember if Google had per-arch builds on Play Store yet, but those also cause issues because people pull those builds and host them on apkg sites, then users have problems when installing them on wrong arch phones. Intel canceled the atom for phones lines days before Microsoft demoed Continuum, which would have been an obvious outlet for an x86 phone. Of course, Microsoft threw in the towel on WM10 before launch too, so maybe Intel wasn't willing to stick it out because they saw Microsoft was going to mess it up. In an alternate reality, the Lumia 950 would be a phone in your pocket and an x86 desktop running real apps on your desk, instead of stuck running app store apps and (pre-chromium) Edge only.