Intel Should Adopt RISC-V

Intel held a meeting in Oregon back in January, attended by then-CEO-to-be Pat Gelsinger. The Verge reported:

“We have to deliver better products to the PC ecosystem than any possible thing that a lifestyle company in Cupertino” makes, Gelsinger reportedly told Intel employees. “We have to be that good, in the future.”

Although this immediately seems like a rallying cry to Intel's workforce to strive for better, this quote seems to hint at a disappointing attitude for Intel to adopt with respect to its competition. (I'm a terrible cynic, it has been said.) I'm choosing to read far too much into these words, considering I've only heard read them third-hand and without the nuance of spoken delivery, but assuming that the first step of winning anything is knowing your opponent, it would be foolish for Intel to dismiss Apple as some kind of engineer-free fashion label.

A less cynical person might highlight that Intel's dismissal of Apple implies that it is placing the blame for their woes of recent years on their own shoulders. I would contend, though, that to place the blame on their own shoulders is to downplay not only Apple's achievements, but others' too: AMD created an incredible micro-architecture, considering their R&D budget, while Intel failed to innovate, and TSMC created a successful silicon process while Intel... didn't.

Additionally, Apple's vertical integration—silicon, hardware, software and services, across the product range—is not to be underestimated. The ongoing change in the market which Apple silicon clearly shows means that Intel's significance is no longer as guaranteed as it previously was. Gelsinger's words seem to have a tinge of righteousness to them, though, as if it's just not right that Intel be lagging behind its competition; that "we're supposed to dominate, we're Intel."

That had me thinking. Assuming Gelsinger's attitude is actually more humble and considered than I've interpreted—it probably is, and many people hold him in high regard^[1]—in which direction would he take Intel?

Let's start with the mobile market: Battery life matters a lot to laptop users, and I get the impression that Arm's simplicity means x86 CPUs are unlikely to ever compete in power efficiency. Indeed, the M1 MacBook Air (with 2560×1600 pixel display) and the 2020 Dell XPS 13 (with 1920×1200 pixel display) have similar battery life, although the MacBook usually lasts 10–20% longer even while driving 1.77× the pixels. The 4K XPS 13 drinks juice at almost twice the rate of its sibling and is widely and deservedly panned. Gelsinger (reportedly) used the words "than any possible thing"—that is, Intel must task itself with producing chips better than anything Apple could possibly produce. Can x86 really manage this?

It's not just the laptop market though. x86 is already non-existent in smartphones and already secondary to Arm in the embedded and IoT markets. I don't know how significant Arm's power efficiency improvement is when compared to top-binned, low-clocked x86 server chips, but if it's significant enough Arm will appeal to datacentre operators too.

I mentioned Intel's recent woes—e.g., AMD's chiplet technology, the 10nm node—but there has also been the steady stream of virtually-unmitigable hardware vulnerabilities. Complexity and legacy are frequent precursors to security problems, and x86 has plenty of both. As new x86 security vulnerabilities inevitably appear, I can easily see business consumers showing interest in something else completely. In fact, Arm already accounts for a small-but-growing portion of server installations.

Perhaps Intel's continued investment in x86 is worth it for them purely to keep AMD in check—as much as Intel can be trusted to do that—but surely getting ahead of the curve is worth more. Such a transition couldn't happen without a generous transition phase, of course, but if the tide is moving towards Arm and RISC-V (or PowerPC, anyone?) Intel mustn't stubbornly hold onto x86 for too long.

Given that Apple has now dragged Adobe, Autodesk, Microsoft^[2], and co. to Arm whether they like it or not, in doing so improving application support on Windows 10 on Arm^[3], I imagine a significant volume of the software work required to support a RISC-V transition has already been done. At least for Arm, the pathway to wider desktop adoption is much clearer now. On the ground, software teams have adapted for multi-architecture integration and testing; platform-specific features have been worked around; and the launch of M1 has been well-received. I would argue these changes have lowered the barrier to adoption of not just Arm, but also RISC-V.

I choose RISC-V specifically not just out of FOSS-brand idealism, but because I can't help but think it makes sense for Intel. Intel has spent the last two decades begrudgingly licensing x86-64 from AMD, and spent even longer being forced to license x86 to AMD. I bet they'd like some fresh air. Since Intel is moving towards further competition with NVIDIA, the latter's still-ongoing acquisition of Arm would at least make Intel uncomfortable about balancing their next decade or two of CPU production on that ISA. If they want fresh air, RISC-V is about as fresh as it gets.

Companies increasingly realise that the simplest and cheapest solution to lot of problems is in fact open collaboration, or at least co-existence. As an anti-example, a hypothetical new proprietary alternative to USB^[4] wouldn't work for anyone, in large part thanks to competition; it just makes more sense to have an industry standard and to allow interoperation. Separately, on the software side, the Open Container Initiative shows extensive industry collaboration and, arguably, the Linux kernel does too, given how much commercial effort is invested in its development. I think competition is critical to the economic viability of an open industry standard, and there's more competition in the CPU market now than there has been historically. AMD, Apple, Huawei, MediaTek, Qualcomm and Samsung are all shipping huge quantities of chips, and out of those Intel is only significantly involved with AMD. Perhaps an open ISA would be best for them all, and give the Arm-dependants an escape from their potential future dependency on notoriously vindictive NVIDIA.

Not only is RISC-V open, but of the six aforementioned companies only Huawei's logo is shown on the RISC-V homepage. RISC-V is immature enough that there is room for a big player to introduce itself, cement its presence in the ecosystem, and influence the future direction of the project. As GitHub's proprietary service has become almost synonymous with Git, Intel has an opportunity to make itself an integral part of the RISC-V ecosystem. Not everything Intel contributes even needs to be open, as GitHub demonstrates. Even so, Intel will incur costs and assume risk being the early bird, but that's sometimes what it takes to catch a worm.

Regarding Intel's future CPUs, a hardware accelerator for x86-to-RISC-V translation would be a valuable feature in an effort to move the industry to RISC-V. Windows and Linux don't have as clear a notion of what constitutes an "app" as macOS, which may complicate the implementation of a competitive Rosetta 2 equivalent on those platforms. I think the computational effort required to execute x86 on Arm or RISC-V is always going to be a bit higher for Windows and Linux, but hardware acceleration could help to mitigate that. HEVC acceleration can be found in CPUs, GPUs and even T2; perhaps accelerated machine code translation will become common in the future.

From what I've read, the RISC–CISC distinction is not quite as clear or significant as it's sometimes made out to be, but arguably Intel and AMD already have plenty of experience building silicon to translate x86 to RISC. Modern CPUs decode complex x86 instructions to a reduced set of instructions; micro-operations. An internal, un-standardised set of micro-ops is hardly RISC-V, but the lessons learnt building the front-end of an x86 CPU would surely be of use in the development of an x86-to-RISC-V accelerator.

Ultimately, Intel can choose to ride x86 into the sunset or switch to something else. There may be several Itanium-shaped scars on Chipzilla from previous failed attempts^[5] to move on, but Intel's opportunity is now. If they hesitate, Arm will only lay claim to the rest of Intel's lunch. Look, Intel—they just announced Armv9!

Footnotes

1. ☝ "His arrival has been met with praise across the spectrum given his background and previous successes". AnandTech.

2. ☝ I can't find much exact information, but it sounds like there was no native support for Office on Windows 10 on Arm until the update for M1.

3. ☝ Linus touched on this in LTT's Surface Pro X vs. M1 MacBook Air video.

4. ☝ Thunderbolt gave this a good shot, and I think it had loftier goals than just being a proprietary USB. Even so, Thunderbolt and USB are set to merge, and it's the latter's name that gets to stay.

5. ☝ Itanium, XScale, iAPX 432, i960, i860. Thanks /u/protonsandneutrons and /u/phire on /r/hardware.