Lab 15, Eve, Hello World from Limbo!

It is our 15-th Lab and it is the time came to make birth of the process Eve, run Dis virtual machine and our first Limbo program!

First create file archrpi.c where we all R-Pi platform specific code. We need to implement kprocchild() call:

static void
linkproc(void)
{
	spllo();
	if (waserror())
		print("error() underflow: %r\n");
	else (*up->kpfun)(up->arg);
	pexit("end proc", 1);
}

void
kprocchild(Proc *p, void (*func)(void*), void *arg)
{
	p->sched.pc = (ulong)linkproc;
	p->sched.sp = (ulong)p->kstack+KSTACK-8;
	p->kpfun = func;
	p->arg = arg;
}

As it is ready we just add initializations that are left to main.c:

	...
	trapinit();
	printinit();

	print("\nARM %ld MHz id %8.8lux\n", (m->cpuhz+500000)/1000000, getcpuid());
	print("Inferno OS %s Vita Nuova\n\n", VERSION);

	procinit();
	links();
	chandevreset();

	eve = strdup("inferno");

	userinit();
	schedinit();

	pl011_puts("to inifinite loop\n\n");
	for (;;);

Where our initialization of first process init0() and run first Dis program:

void
init0(void)
{
	Osenv *o;
	char buf[2*KNAMELEN];

	up->nerrlab = 0;

	print("Starting init0()\n");
	spllo();

	if(waserror())
		panic("init0 %r");

	/* These are o.k. because rootinit is null.
	 * Then early kproc's will have a root and dot. */

	o = up->env;
	o->pgrp->slash = namec("#/", Atodir, 0, 0);
	cnameclose(o->pgrp->slash->name);
	o->pgrp->slash->name = newcname("/");
	o->pgrp->dot = cclone(o->pgrp->slash);

	chandevinit();

	if(!waserror()){
		ksetenv("cputype", "arm", 0);
		snprint(buf, sizeof(buf), "arm %s", conffile);
		ksetenv("terminal", buf, 0);
		poperror();
	}

	poperror();

	disinit("/osinit.dis");
}

void
userinit(void)
{
	Proc *p;
	Osenv *o;

	p = newproc();
	o = p->env;

	o->fgrp = newfgrp(nil);
	o->pgrp = newpgrp();
	o->egrp = newegrp();
	kstrdup(&o->user, eve);

	strcpy(p->text, "interp");

	p->fpstate = FPINIT;

	/*	Kernel Stack
		N.B. The -12 for the stack pointer is important.
		4 bytes for gotolabel's return PC */
	p->sched.pc = (ulong)init0;
	p->sched.sp = (ulong)p->kstack+KSTACK-8;

	ready(p);
}

Now go to folder ../init/ and create simple Limbo program rpiinit.b:

implement Init;

include "sys.m";
    sys:    Sys;

Bootpreadlen: con 128;

Init: module
{
    init:   fn();
};

init()
{
    sys = load Sys Sys->PATH;
    sys->print("Hey, this is Hello World from Dis!\n\n");
}

Now edit platform definition file rpi, section init and section root to use rpiinit.b:

...
init
    rpiinit

root
    /chan   /
    /dev    /
    /dis    /
    /env    /
    /fd     /
    /net    /
    /prog   /
    /dis/lib
    /dis/disk
    /osinit.dis

Compile, start Raspberry Pi device with expectations and:

Load address: 0x7fe0
Loading: T #T #####################################
done
Bytes transferred = 552620 (86eac hex)
## Starting application at 0x00008000 ...
Entered main() at 00009114 with SP=00002FE8
Clearing Mach:  00002000-00002060
Clearing edata: 00065B08-0006CC30
Conf: top=134217728, npage0=32659, ialloc=26750976, nproc=735

ARM 0 MHz id 410fb767
Inferno OS Fourth Edition (20121207) Vita Nuova

Starting init0()
Initial Dis: "/osinit.dis"
Hey, this is Hello World from Dis!

Wow, Success!

FILES:
rpi
dat.h
main.c
trap.c
mkfile
archrpi.c
../init/rpiinit.b