rewrite configuration to confaddr for eventual quick reboot for amd64.

this code takes a different approach than plan9.  plan 9 builds a malloc'd
buffer of null terminated names and values.  then writeconf() replaces the
nulls with alternating = and \n.

this code simply has devenv stuff the environment with = and \n delimiters
directly in a provided buffer (no malloc).

Reference: /n/atom/patch/applied2013/nixwriteconf
Date: Mon Dec 30 21:24:10 CET 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/fns.h	Mon Dec 30 21:20:30 2013
+++ /sys/src/nix/k10/fns.h	Mon Dec 30 21:20:31 2013
@@ -119,6 +119,7 @@
 void	rdrandbuf(void*, usize);
 u64int	rdtsc(void);
 void	trput(u64int);
+void	writeconf(void);
 void	wrmsr(u32int, u64int);
 
 int	cas32(void*, u32int, u32int);
@@ -159,7 +160,6 @@
  * i8259.c
  */
 int	i8259init(int);
-int	i8259isr(int);
 
 /*
  * mp.c
--- /sys/src/nix/k10/options.c	Mon Dec 30 21:20:32 2013
+++ /sys/src/nix/k10/options.c	Mon Dec 30 21:20:33 2013
@@ -36,28 +36,39 @@
 parseoptions(void)
 {
 	long i, n;
-	char *cp, *line[Maxconf];
+	char *p, *line[Maxconf];
 
 	/*
 	 *  parse configuration args from dos file plan9.ini
 	 */
-	cp = BOOTARGS;	/* where b.com leaves its config */
-	cp[BOOTARGSLEN-1] = 0;
+	p = BOOTARGS;	/* where b.com leaves its config */
+	p[BOOTARGSLEN-1] = 0;
 
-	n = getfields(cp, line, Maxconf, 1, "\n");
+	n = getfields(p, line, Maxconf, 1, "\n");
 	for(i = 0; i < n; i++){
 		if(*line[i] == '#')
 			continue;
-		cp = strchr(line[i], '=');
-		if(cp == nil)
+		p = strchr(line[i], '=');
+		if(p == nil)
 			continue;
-		*cp++ = '\0';
+		*p++ = '\0';
 		cfg[ncfg].name = line[i];
-		cfg[ncfg].val = cp;
+		cfg[ncfg].val = p;
 		ncfg++;
 	}
 }
 
+void
+writeconf(void)
+{
+	char *p, *e;
+	int n;
+
+	e = BOOTARGS+BOOTARGSLEN;
+	p = confenv(BOOTARGS, e);
+	memset(p, 0, e-p);
+}
+
 static void
 cmdline(void)
 {
@@ -179,11 +190,11 @@
 		if(cistrncmp(p, "type=", 5) == 0)
 			pci->type = p + 5;
 		else if(cistrncmp(p, "port=", 5) == 0)
-			pci->port = strtoul(p+5, &p, 0);
+			pci->port = strtoull(p+5, &p, 0);
 		else if(cistrncmp(p, "irq=", 4) == 0)
 			pci->irq = strtoul(p+4, &p, 0);
 		else if(cistrncmp(p, "mem=", 4) == 0)
-			pci->mem = strtoul(p+4, &p, 0);
+			pci->mem = strtoull(p+4, &p, 0);
 		else if(cistrncmp(p, "tbdf=", 5) == 0)
 			pci->tbdf = strtotbdf(p+5, &p, 0);
 	}
--- /sys/src/nix/port/portfns.h	Mon Dec 30 21:20:34 2013
+++ /sys/src/nix/port/portfns.h	Mon Dec 30 21:20:35 2013
@@ -41,6 +41,7 @@
 void		cmderror(Cmdbuf*, char*);
 int		cmount(Chan**, Chan*, int, char*);
 Block*		concatblock(Block*);
+char*		confenv(char*, char*);
 int		consactive(void);
 void		(*consdebug)(void);
 void		(*consputs)(char*, int);
@@ -114,7 +115,6 @@
 void		freeblist(Block*);
 int		freebroken(void);
 void		freepte(Segment*, Pte*);
-char*		getconfenv(void);
 int		getpgszi(usize);
 void		gotolabel(Label*);
 int		haswaitq(void*);
--- /sys/src/nix/port/devenv.c	Mon Dec 30 21:20:36 2013
+++ /sys/src/nix/port/devenv.c	Mon Dec 30 21:20:37 2013
@@ -396,45 +396,25 @@
 	cclose(c);
 }
 
-/*
- * Return a copy of configuration environment as a sequence of strings.
- * The strings alternate between name and value.  A zero length name string
- * indicates the end of the list
- */
-char *
-getconfenv(void)
+/* copy configuration environment to the given buffer. */
+char*
+confenv(char *p, char *e)
 {
-	Egrp *eg = &confegrp;
-	Evalue *e;
-	char *p, *q;
-	int i, n;
+	int i;
+	Egrp *eg;
+	Evalue *v;
 
+	eg = &confegrp;
 	rlock(eg);
 	if(waserror()) {
 		runlock(eg);
 		nexterror();
 	}
-
-	/* determine size */
-	n = 0;
-	for(i=0; i<eg->nent; i++){
-		e = eg->ent[i];
-		n += strlen(e->name) + e->len + 2;
-	}
-	p = malloc(n + 1);
-	if(p == nil)
-		error(Enomem);
-	q = p;
 	for(i=0; i<eg->nent; i++){
-		e = eg->ent[i];
-		strcpy(q, e->name);
-		q += strlen(q) + 1;
-		memmove(q, e->value, e->len);
-		q[e->len] = 0;
-		/* move up to the first null */
-		q += strlen(q) + 1;
+		v = eg->ent[i];
+		p = seprint(p, e, "%s=%*s\n", v->name, v->len, v->value);
 	}
-	*q = 0;
+	*p = 0;
 
 	poperror();
 	runlock(eg);