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Comment by RetroTechie | Hacker News Reader

> such as Qualcomm deciding to just release their version anyway.

Qualcomm must resolve this within RISC-V International somehow. Going its own way would designate those products as non-conformant to RV spec, not passing test suites, not allowed to carry RISC-V logo or claim "RISC-V compatible", etc. With all the software headaches that would result in. Or 3rd party vendors avoiding such Qualcomm products.

So this comes down to "convince majority of RISC-V members Qualcomm's proposal is better". Or failing that, just deal with it.

Whatever happens, chances are slim that backward compatibility with existing implementations & software would be broken @ this point. So creating some kind of alternative profile seems like the most sane option?

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Not having the compressed instruction set extension wouldn't make Qualcomm's CPUs not RISC-V. They just wouldn't be compliant with the RVA23 profile.

>wouldn't make Qualcomm's CPUs not RISC-V.

Only if they use the op space reserved for custom extensions.

If they don't and instead step all over space that belongs to C, then they would indeed not be RISC-V.

Yeah, when I wrote that, I didn't realize they were also arguing for an alternate extension that would add address modes and the like. If they fail to add this to the standard, but go ahead with implementing their extension anyway, then their CPUs would be RISC-V but with a custom instruction set extension. RV64g + their custom stuff.

Only if they use custom extension encoding space exclusively, and do not step over standard encoding space, such as what's reserved for the C extension.

Which is what I understand they're doing. Thus could not be called RISC-V.

> not allowed to carry RISC-V logo or claim "RISC-V compatible", etc

If Qualcomm’s offering is performant (in its dollars, power and speed mix) and Qualcomm keeps it open enough (I think this is at the moment, as they are using an instruction set that anybody can copy), would Qualcomm’s customers care about that? If so, would Qualcomm?

The largest possible concern I see is that customers would have to be convinced that Qualcomm can deliver good compilers that don’t inadvertently spit out instructions not supported by their somewhat off-beat hardware.

I think costumers have a few issus. First of all, one of the biggest reason consumer companies want RISC-V is because they can select between multiple vendors. Qualcomm would very likely be the only high performance implementation of their standard. So you are binding yourself to Qualcomm.

Second, the software ecosystem is huge, far more then compiles. And given how everybody today uses open source, making all that available for Qualcomm seems like a losing effort.

Is Qualcomm gone pay to make Android Qualcomm-RISC-V ready. Are they gone provide advanced verification suits. Formal analysis and all that stuff?

To be fair here you have historically been able to bork certain Qualcomm devices running legitimate ARM code due to them not supporting all the instructions they claimed. (And the BSP would do sneaky things to attempt to obfuscate this).

Qualcomm absolutely have the market power in the Android space to redefine a new open ISA if they want to though.

>Qualcomm absolutely have the market power in the Android space to redefine a new open ISA if they want to though.

Only if Google allows them. Which is unlikely.

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