(Mis)understanding RISC-V ecalls and syscalls
After spending some time with emuriscv and attempting to boot Linux into a shell I realized that I’m doing something really wrong regarding system calls. RISC-V offers an ecall (Environment Call) instruction to implement system calls. These are basically requests made by a lower privileged code (user mode) to execute higher privileged code (kernel). Or, in some other case, the kernel itself can be the lower privileged code and it would invoke the machine mode code with an ecall.
Source: jborza.com