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Arm is canceling Qualcomm's chip design license

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Re: Arm is canceling Qualcomm's chip design license

#301

Post by cesarb »

shash wrote: post #238
coder543 wrote: post #75

Earlier quoted context omitted.

> 1. Qualcomm develops a chip that competitive in performance to ARM Virtually all high performance processors these days operate on their own internal “instructions”. The instruction decoder at the very front of the pipeline that actually sees ARM or RISC-V or whatever is a relatively small piece of logic. If Qualcomm were motivated, I believe they could swap ISAs relatively easily on their flagship processors, and…

> Virtually all high performance processors these days operate on their own internal “instructions”. The instruction decoder at the very front of the pipeline that actually sees ARM or RISC-V or whatever is a relatively small piece of logic. You're talking essentially about microcode; this has been the case for decades, and isn't some new development. However, as others have pointed out, it's not _as_ simple as just…

> > Virtually all high performance processors these days operate on their own internal “instructions”. The instruction decoder at the very front of the pipeline that actually sees ARM or RISC-V or whatever is a relatively small piece of logic.

> You're talking essentially about microcode; this has been the case for decades, and isn't some new development.

Microcode is much less used nowadays than in the past. For instance, several common desktop processors have only a single instruction decoder capable of running microcode, with the rest of the instruction decoders capable only of decoding simpler non-microcode instructions. Most instructions on typical programs are decoded directly, without going through the microcode.

> However, as others have pointed out, it's not _as_ simple as just swapping out the decoder

Many details of an ISA extend beyond the instruction decoder. For instance, the RISC-V ISA mandates specific behavior for its integer division instruction, which has to return a specific value on division by zero, unlike most other ISAs which trap on division by zero; and the NaN-boxing scheme it uses for single-precision floating point in double-precision registers can be found AFAIK nowhere else. The x86 ISA is infamous for having a stronger memory ordering than other common ISAs. Many ISAs have a flags register, which can be set by most arithmetic (and some non-arithmetic) instructions. And that's all for the least-privileged mode; the supervisor or hypervisor modes expose many more details which differ greatly depending on the ISA.

Re: Arm is canceling Qualcomm's chip design license

#302

Post by dehugger »

delfinom wrote: post #272
rickdeckard wrote: post #257

Earlier quoted context omitted.

The merge of the Qualcomm architecture with the Nuvia IP they acquired, which was created under a far-reaching license ARM granted to Nuvia. Combining both creates a custom architecture different from ARMs consolidated and harmonized designs offered to licensees (i.e. Blackhawk or Cortex-X). The IP of Nuvia was not supposed to be used in all the use-cases that Qualcomm intends to deploy it in (and moreover there is s…

So when is ARM going after Apple for their custom architecture? Afai, Q hasn't diverged from the standard instruction set at all in the Oryon snapdragons.

Presumably Apple didn't violate the terms of their own licensing agreement with ARM.

Re: Arm is canceling Qualcomm's chip design license

#303

Post by eqvinox »

brucehoult wrote: post #14
nahnahno wrote: post #7

Earlier quoted context omitted.

I don’t think they have a plan B. Architectures take half a decade of work. Porting from risc-v to arm is not a matter of a backup plan, it’s that of a very costly pivot.

Qualcomm have a Plan B. This time last year they were all over the RISC-V mailing lists, trying to convince everyone to drop the "C" extension from RVA23 because (basically confirmed by their employees) it was not easy to retrofit mildly variable length RISC-V instructions (2 bytes and 4 bytes) to the Aarch64 core they acquired from Nuvia. At the same time, Qualcomm proposed a new RISC-V extension that was pretty muc…

> Dropping "C" overnight and thus making all existing Linux software incompatible is completely out of the question.

For general purpose Linux, I agree. But if someone makes Android devices and maintains that for RISC-V… that's basically a closed, malleable ecosystem where you can just say "f it, set this compiler option everywhere".

But also, yes, another commenter pointed out C brings some power savings, which you'd presumably want on your Android device…

Re: Arm is canceling Qualcomm's chip design license

#304

Post by cesarb »

brucehoult wrote: post #210
eggsome wrote: post #183

Earlier quoted context omitted.

What do you mean by Plan B? From what you've just said it sounds like their proposal was rejected, so there is no plan b now?

They can roll their sleeves up and do the small amount of work that they tried to persuade everyone else was not necessary. And I'm sure they will have done so. It's not that hard to design a wide decoder that can decode mixed 2-byte and 4-byte instructions from a buffer of 32 or 64 bytes in a clock cycle. I've come up with the basic schema for it and written about it here and on Reddit a number of times. Yeah, it's…

> Yeah, it's a little harder than for pure fixed-width Arm64, but it is massively massively easier than for amd64.

For those who haven't read the details of the RISC-V ISA: the first two bits of every instruction tell the decoder whether it's a 16-bit or a 32-bit instruction. It's always in that same fixed place, there's no need to look at any other bit in the instruction. Decoding the length of a x86-64 instruction is much more complicated.

Re: Arm is canceling Qualcomm's chip design license

#305

Post by dagmx »

zbshqoa wrote: post #269
dagmx wrote: post #116

Earlier quoted context omitted.

ARM licenses cores for both CPU and GPU, not just the architecture. There are not “plenty of ARM chips designed by multiple companies”, almost all of them except for Apple (and now Qualcomm) use ARMs off the shelf design.

https://www.arm.com/markets/computing-infrastructure/cloud-c... > Annapurna Labs, Ampere Computing, NVIDIA, Intel, Marvell, Pensando Systems, and others use Arm Neoverse and Arm technologies to create cloud-optimized CPUs and DPUs. https://en.m.wikipedia.org/wiki/ARM_architecture_family > Companies that have designed cores that implement an ARM architecture include Apple, AppliedMicro (now: Ampere Computing), Broadco…

The first list is basically what I said: they use licensed core designs and don’t make their own.

The second list is out of date. Intel has completely pulled out of ARM earlier this year and most of the others do not actually design their own ARM cores anymore. It’s become a lot less common in the ARMv8+ era.

Re: Arm is canceling Qualcomm's chip design license

#306

Post by dagmx »

adrian_b wrote: post #233
dagmx wrote: post #204

Earlier quoted context omitted.

They’re only losing their license to make custom cores. They’re still free to use ARMs own cores. The reason being that ARM gave Nuvia a license to design cores at a specific rate, then Qualcomm bought them to use those cores. ARM claims that the license to design cores does not have a transferable rate to it.

Now Qualcomm does not want to continue to use any Arm cores, both because their own cores are better and because that would save them the cost for royalties. Obviously, Arm tries to prevent Qualcomm from using their own cores, because this time Arm would lose a major source of their revenue if Qualcomm stopped licensing cores. When Arm has given architectural licenses to Qualcomm and Nuvia, they were not worried abou…

There’s a LOT of conjecture in your comment.

Your very first line is one to begin with.

ARM also doesn’t seem to care if QC design their own cores. They just care that they renegotiate the royalty agreement. This is clear if you actually read their statements.

Re: Arm is canceling Qualcomm's chip design license

#307

Post by dvdkon »

yalogin wrote: post #189
hajile wrote: post #52

Earlier quoted context omitted.

Qualcomm doesn't have nearly as much to lose as ARM does and they know it. Qualcomm is almost certainly ARM's biggest customer. If ARM loses, Qualcomm doesn't have to pay out. If ARM wins, Qualcomm moves to RISC-V and ARM loses even harder in the long-term. The most likely outcome is that Qualcomm agrees to pay a slight bit more than they are currently paying, but nowhere near what ARM is demanding and in the meantim…

Moving to a whole new architecture is really really hard, no? The operating systems and applications all need to be ported. Just because Qualcomm cannot be friends with arm, every single Qualcomm customer from google to some custom device manufacturer needs to invest years and millions to move to a new architecture? Unless I am fundamentally misunderstanding this, it seems like something they won’t be able to achieve…

Android already supports RISC-V, so while migrating an SOC to it is not painless (third-party binaries, device-specific drivers...), the hard work of porting the operating system itself to the ISA is done.

Re: Arm is canceling Qualcomm's chip design license

#308

Post by dagmx »

snvzz wrote: post #221
dagmx wrote: post #163

Earlier quoted context omitted.

I think you just ignored the rest of my comment though which specifically addresses why I don’t think just relying on translation is an effective strategy. Users aren’t going to switch to a platform that has lower compatibility when the incumbent has almost as good efficiency and performance.

>when the incumbent has almost as good efficiency and performance. The incumbent is the only two companies -Intel and AMD- that can make x86 hardware. The alternative is the rest of the industry. Thus having a migration path should be plenty on its own. Intel and AMD can both join by making RISC-V or ARM hardware themselves. My take is that they will too, eventually, come around. Or they'll just disappear from releva…

The incumbent is not just x86 but now ARM as well.

You have to think in network effects. You mention “the rest of the industry” yet ignore that it’s mostly arm , which would make arm the incumbent.

x86 is the king for windows. But ARM has massive inroads with mobile, and now desktop with macOS, and servers with Amazon/Nvidia etc

There’s a lot better incentive to support ARM than RISC-V for software developers. It isn’t one or the other , but it is a question of resources.

Intel and AMD seem fine turning x86 around when threatened as can be seen by Lunar Lake and Stryx Point. Both have been good enough to steal QC’s thunder. You don’t think ARM manufacturers will do the same to RISC-V?

TBH most of your arguments for RISC-V adoption seem to start from the position that it’s inevitable AND that competing platforms won’t also improve.

Re: Arm is canceling Qualcomm's chip design license

#309

Post by ahoka »

biosboiii wrote: post #203
hajile wrote: post #52

Earlier quoted context omitted.

Qualcomm doesn't have nearly as much to lose as ARM does and they know it. Qualcomm is almost certainly ARM's biggest customer. If ARM loses, Qualcomm doesn't have to pay out. If ARM wins, Qualcomm moves to RISC-V and ARM loses even harder in the long-term. The most likely outcome is that Qualcomm agrees to pay a slight bit more than they are currently paying, but nowhere near what ARM is demanding and in the meantim…

Thing is businesses don't work like side-projects do. Qualcomm is more or less a research company, the main cost of their business is paying engineers to build their modems/SoCs/processors/whatever. They have been working with ARM for the last, I dont know, 20 years? Even if they manage to switch to RISC-V, and each employee has negative performance impact of like 15% for 2-3 years this ends up in billions of dollars…

Try Java 1.8.

Re: Arm is canceling Qualcomm's chip design license

#310

Post by dagmx »

numpad0 wrote: post #230
dagmx wrote: post #23

Earlier quoted context omitted.

Maybe fine for Android but this will set their windows plans back another decade if it happens It has taken them that long to make arm be a thing on windows and that’s building on people porting stuff to arm for Mac to finally get momentum. RISC-V with windows will be an eternity to be feasible.

Just something I as a random person been thinking, how likely is next version of Windows _not_ going to be something Linux-based with WINE+Bochs preinstalled? Windows branding is now forever tied with x86/x64 Win32 legacy compatibility, meanwhile WSL had captured back a lot of webdevs from Mac. Google continues to push Chrome, but Electron continues to grow side by side. Lots of stuff happening with AI on Linux too,…

I think it’s almost certain that Microsoft will not be changing their kernel to Linux.

I think you’re over estimating what percentage of users use WSL. They’re an insignificant fraction of the user base.

And with games, I think you’re also overestimating how good the translation layers like Proton are, and how rapidly Microsoft advance DX as well.

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