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A comment on Qualcomm – one of Arm’s biggest customers – starts a RISC-V joint venture. Parent comment

Re:Qualcomm – one of Arm’s biggest customers – starts a RISC... by snvzz on Sunday August 06, 2023 @12:00PM (#37023307)
>SBI, which is RISCV's poor-man's implementation of x86 SMM,

SMM is totally opaque and does whatever it wants, kidnapping the cpu and giving it back after a random amount of time if at all. Fuck determinism or meeting any sort of hard realtime requirements. It hides bugs and architecture details from the OS, and it often can't even be disabled.

SBI serves a similar role, without the opacity. OS can take requests to it, and even take over all its roles. It has been co-designed by hardware and software (operating systems and embedded) people across the industry, both companies and independent members. It's not even comparable.

Go read the SBI 1.0 spec, and the SBI 2.0 draft.

[ Parent | on HN ]
Re:Qualcomm – one of Arm’s biggest customers – starts a RISC... by pgeorgi on Sunday August 06, 2023 @01:04PM (#37024095)
This is a thread about Qualcomm looking into RISC-V. Seeing how "great" their ARM-based designs are, they will manage to make a real mess out of SBI soon enough and there will be weeping and gnashing of teeth.

I'll stock up on my popcorn supplies, this will be fun to watch from a distance.

[ Parent | on HN ]
Re:Qualcomm – one of Arm’s biggest customers – starts a RISC... by snvzz on Sunday August 06, 2023 @01:12PM (#37024212)
Nevermind about making a non-compliant SBI implementation.

Why make an implementation in the first place? There's no reason to use anything else than opensbi.

[ Parent | on HN ]
Re:Qualcomm – one of Arm’s biggest customers – starts a RISC... by pgeorgi on Sunday August 06, 2023 @01:19PM (#37024304)
Because Qualcomm _really_ dislikes letting others take a look at their (usually very boring) secret sauce. Even partners working on projects shoveling revenue counted with a sizable number of digits their way.

That's also why QCSBI (or whatever they'll call it) won't be replaced by the kernel even though the architecture theoretically allows for it: That would be ceding control.

[ Parent | on HN ]