|
|
|
|
|
|
by unethical_ban
1036 days ago
|
|
|
I don't understand what ARM does. They have designed a processor architecture that is RISC-style. For some companies, ARM sells the design and others manufacture the chip. So what do Apple and Qualcomm get out of it, if they design their own architecture? Is apple tacking on proprietary extensions or instructions? Why didn't apple design a CPU architecture from the ground up ala RISC-V? |
|
|
An ISA is the Instruction Set Architecture, the interface between software and hardware.
A microarchitecture is a hardware implementation of an ISA.
RISC-V is an ISA.
ARM is a company that has both an ISA (actually several, but their current is ARMv9) and a bunch of microarchitectures.
Their business model is to license their IP:
- They may license you a microarchitecture, so that you can include it in your chip's design.
- They may license you the ISA, so you can implement your own microarchitecture for the ISA. Note that you can't then license your microarchitecture to others, that's ARM's sole privilege.
RISC-V's instruction space has some room for custom extensions. Thus it can be adapted to find specific needs, without asking for permission nor opting out of the strongest software ecosystem which RISC-V is rapidly building.
But while RISC-V is pretty good technically, enabling the best processors, what's most disruptive is that it is an open ISA.
It means there's now an open market with RISC-V microarchitectures to license, from a range of vendors. There's also some open source microarchitectures.
Microarchitecture licensing aside, there's an ecosystem of companies offering related services, such as helping you verify your designs, trace your code and so on.