Priviledged instruction set

[BrunoLevy]

1. fully implement instructions to manipulate the CSRs
2. two levels of privilege, ECALL and EBREAK, implement FEMTOS syscalls, SDCard file access and terminal.
3. three levels of privilege
4. MMU
5. run Linux Links: https://github.com/BrunoLevy/learn-fpga/blob/master/FemtoRV/TUTORIALS/priviledged.md

[BrunoLevy]

Let us start with a very minimalistic implementation, that would fit in the miniRV32 as an option, with:

• fixed exception handler address
• only mepc Then implement RV32M and RV32C with it.