Curious: What does the "imac" stand for in the architecture target name ?
IMAC are the RISC-V extensions supported:
I = Base integer instruction set, 32-bit
M = Standard extension for integer multiplication and division
A = Standard extension for atomic instructions
C = Standard extension for compressed instructions
https://en.wikipedia.org/wiki/RISC-V#ISA_base_and_extensions
There are a few lettered extensions to the base RV32I instruction set. e.g.:
* https://docs.riscv.org/reference/isa/unpriv/m-st-ext.html
where did you find it?
IMAC are the RISC-V extensions supported:
I = Base integer instruction set, 32-bit
M = Standard extension for integer multiplication and division
A = Standard extension for atomic instructions
C = Standard extension for compressed instructions
https://en.wikipedia.org/wiki/RISC-V#ISA_base_and_extensions