Startup and Organization
Some critical files include:
Kernel
entry.S which sets up the stack for C code to run
- There’s a line, csrr a1, mhartid, which reads the hardware
thread (hart) into a1. This is because there are multiple threads
and they all need to have different stacks.
start.cwhich starts the computer in machine mode
main.c which starts the OS in supervisor mode, sets up and runs the
kernel. There’s different code that runs based on if the current core is
the first core (cpuid() == 0), because the first core has to set up
the kernel, whereas all the rest wait and then get scheduled afterwards.
User
initcode.S which contains code that execs /init, and sets up argc
and argv for a user process.