3 ms·
They both use U74, but different versions. The one in JH7110 is the 2021Q1 version, AIUI. Besides faster, it also added B extension.
by snvzz 4y ago
They both use U74, but different versions.
The one in JH7110 is the 2021Q1 version, AIUI.
Besides faster, it also added B extension.
- zu2_ 4y agoNo. VisionFive2's RISC-V CPU does not have the B extension. I confirmed it on the actual device. $ cat /proc/cpuinfo processor : 0 hart : 2 isa : rv64imafdc mmu : sv39 uarch : sifive,u74-mc
- snvzz 4y agoAs you say this, I realize I can't find anywhere that it does. I do not know why I thought it did. Possibly as U74-MC[0] supports that option. Interestingly, I also took a look at RVA22[1], and found it requires Zbb but not the whole B. Your /proc/cpuinfo isn't listing Z* extensions. Maybe lscpu output would be more detailed? 0. https://www.sifive.com/cores/u74-mc https://www.sifive.com/cores/u74-mc 1. https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc#rva22u64-mandatory-base https://github.com/riscv/riscv-profiles/blob/main/profiles.a...
- zu2_ 4y agoOh, I was mistaken. I've verified that at least the rev instruction works (tested on clang -march=rv64imafdcb0p94).