update mips emulator for routerboard

Reference: /n/atom/patch/applied2013/viupd
Date: Wed Jul 31 17:25:36 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/vi/vi.c	Wed Jul 31 17:25:19 2013
+++ /sys/src/cmd/vi/vi.c	Wed Jul 31 17:25:19 2013
@@ -2,6 +2,7 @@
 #include <libc.h>
 #include <bio.h>
 #include <mach.h>
+#include <tos.h>
 #define Extern
 #include "mips.h"
 
@@ -291,12 +292,22 @@
 initstk(int argc, char *argv[])
 {
 	ulong size;
-	ulong sp, ap;
+	ulong sp, ap, tos;
 	int i;
 	char *p;
 
 	initmap();
-	sp = STACKTOP - 4;
+	tos = STACKTOP - sizeof(Tos)*2;	/* we'll assume twice the host's is big enough */
+	sp = tos;
+	for (i = 0; i < sizeof(Tos)*2; i++)
+		putmem_b(tos + i, 0);
+
+	/*
+	 * pid is second word from end of tos and needs to be set for nsec().
+	 * we know mips is a 32-bit cpu, so we'll assume knowledge of the Tos
+	 * struct for now, and use our pid.
+	 */
+	putmem_w(tos + 4*4 + 2*sizeof(ulong) + 3*sizeof(uvlong), getpid());
 
 	/* Build exec stack */
 	size = strlen(file)+1+BY2WD+BY2WD+BY2WD;	
@@ -306,7 +317,7 @@
 	sp -= size;
 	sp &= ~3;
 	reg.r[29] = sp;
-	reg.r[1] = STACKTOP-4;	/* Plan 9 profiling clock */
+	reg.r[1] = tos;			/* Plan 9 profiling clock, etc. */
 
 	/* Push argc */
 	putmem_w(sp, argc+1);
--- /sys/src/cmd/vi/mips.h	Wed Jul 31 17:25:20 2013
+++ /sys/src/cmd/vi/mips.h	Wed Jul 31 17:25:21 2013
@@ -229,7 +229,7 @@
 Extern		int rtrace;
 
 /* Plan9 Kernel constants */
-#define	BY2PG		4096
+#define	BY2PG		(16*1024)
 #define BY2WD		4
 #define UTZERO		0x1000
 #define STACKTOP	0x80000000
--- /sys/src/cmd/8l/elf.h	Wed Jul 31 17:25:21 2013
+++ /sys/src/cmd/8l/elf.h	Wed Jul 31 17:25:22 2013
@@ -45,6 +45,7 @@
 	I860 = 7,		/* Intel i860 */
 	MIPS = 8,		/* Mips R2000 */
 	S370 = 9,		/* Amdhal	*/
+	MIPSR4K = 10,		/* Mips R4000 */
 	SPARC64 = 18,		/* Sun SPARC v9 */
 	POWER = 20,		/* PowerPC */
 	POWER64 = 21,		/* PowerPC64 */