make room for big Tos structure.  this prevents *init* from dying with
invalid memory references.

Reference: /n/atom/patch/applied2013/9tossize
Date: Sat Sep 21 20:39:48 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/bitsy/main.c	Sat Sep 21 20:39:12 2013
+++ /sys/src/9/bitsy/main.c	Sat Sep 21 20:39:13 2013
@@ -145,7 +145,7 @@
 	 *  trap.c's syscall() work even when we have less than the
 	 *  max number of args.
 	 */
-	sp = (uchar*)base + BY2PG - sizeof(Sargs);
+	sp = (uchar*)base + BY2PG - Ustkheadroom;
 
 	bootpath = pusharg("/boot/boot");
 	ac = 0;
--- /sys/src/9/kw/main.c	Sat Sep 21 20:39:14 2013
+++ /sys/src/9/kw/main.c	Sat Sep 21 20:39:15 2013
@@ -7,6 +7,7 @@
 #include "init.h"
 #include "arm.h"
 #include <pool.h>
+#include <tos.h>
 
 #include "reboot.h"
 
@@ -23,6 +24,14 @@
 #define	MAXCONF		64
 #define MAXCONFLINE	160
 
+enum {
+	Maxmem	= 512*MB,			/* limited by address ranges */
+	Minmem	= 256*MB,			/* conservative default */
+
+	/* space for syscall args, return PC, top-of-stack struct */
+	Ustkheadroom	= sizeof(Sargs) + sizeof(uintptr) + sizeof(Tos),
+};
+
 #define isascii(c) ((uchar)(c) > 0 && (uchar)(c) < 0177)
 
 uintptr kseg0 = KZERO;
@@ -224,13 +233,19 @@
 {
 	Spiregs *rp = (Spiregs *)soc.spi;
 
+	if (probeaddr(soc.spi) < 0)
+		return;
 	rp->ictl |= Csnact;
 	coherence();
 	rp->icfg |= Dirrdcmd | 3<<8;	/* fast reads, 4-byte addresses */
 	rp->icfg &= ~Bytelen;		/* one-byte reads */
 	coherence();
 
-//	print("spi flash at %#ux: memory reads enabled\n", PHYSSPIFLASH);
+	print("spi flash ignored: ctlr %#p, data %#ux", rp, PHYSSPIFLASH);
+	mmuidmap(PHYSSPIFLASH, 1);
+	if (probeaddr(PHYSSPIFLASH) < 0)
+		print(" (no response)");
+	print(": memory reads enabled\n");
 }
 
 void	archconsole(void);
--- /sys/src/9/kw/fns.h	Sat Sep 21 20:39:16 2013
+++ /sys/src/9/kw/fns.h	Sat Sep 21 20:39:17 2013
@@ -57,6 +57,7 @@
 extern void l2cacheuwbse(void*, int);
 extern void lastresortprint(char *buf, long bp);
 extern int log2(ulong);
+extern void mmuidmap(uintptr phys, int mbs);
 extern void mmuinvalidate(void);		/* 'mmu' or 'tlb'? */
 extern void mmuinvalidateaddr(u32int);		/* 'mmu' or 'tlb'? */
 extern u32int pidget(void);
@@ -86,6 +87,7 @@
 extern void mmuinit(void);
 extern void touser(uintptr);
 extern void trapinit(void);
+extern vlong probeaddr(uintptr);
 
 extern int fpiarm(Ureg*);
 extern void fpuinit(void);
--- /sys/src/9/kw/mem.h	Sat Sep 21 20:39:18 2013
+++ /sys/src/9/kw/mem.h	Sat Sep 21 20:39:18 2013
@@ -130,12 +130,12 @@
 
 /* from 0x80000000 up is uncached by L2 (see archkw.c) */
 #define PHYSCESASRAM	0xc8010000
-// #define PHYSSPIFLASH	0xe8000000		/* ignore spi flash */
+#define PHYSNAND2	0xd8000000		/* guru */
+#define PHYSSPIFLASH	0xe8000000		/* optional spi flash (dream) */
 /* this address is configured by u-boot, and is 0xd0000000 at reset */
 #define PHYSIO		0xf1000000		/* internal registers */
 #define PHYSCONS	(PHYSIO + 0x12000)	/* uart */
 #define PHYSNAND1	0xf9000000		/* sheeva/openrd (remapped) */
-#define PHYSNAND2	0xd8000000		/* guru */
 #define PHYSBOOTROM	0xffff0000		/* boot rom */
 
 #define FLASHSIZE	(512*MiB)		/* but not addressed linearly */
--- /sys/src/9/omap/main.c	Sat Sep 21 20:39:20 2013
+++ /sys/src/9/omap/main.c	Sat Sep 21 20:39:21 2013
@@ -7,6 +7,7 @@
 
 #include "init.h"
 #include <pool.h>
+#include <tos.h>
 
 #include "reboot.h"
 
@@ -25,6 +26,9 @@
 
 enum {
 	Minmem	= 256*MB,			/* conservative default */
+
+	/* space for syscall args, return PC, top-of-stack struct */
+	Ustkheadroom	= sizeof(Sargs) + sizeof(uintptr) + sizeof(Tos),
 };
 
 #define isascii(c) ((uchar)(c) > 0 && (uchar)(c) < 0177)
@@ -485,7 +489,7 @@
 	 * of the argument list checked in syscall.
 	 */
 	i = oargblen+1;
-	p = UINT2PTR(STACKALIGN(base + BY2PG - sizeof(up->s.args) - i));
+	p = UINT2PTR(STACKALIGN(base + BY2PG - Ustkheadroom - i));
 	memmove(p, oargb, i);
 
 	/*
--- /sys/src/9/teg2/main.c	Sat Sep 21 20:39:22 2013
+++ /sys/src/9/teg2/main.c	Sat Sep 21 20:39:24 2013
@@ -7,6 +7,7 @@
 
 #include "init.h"
 #include <pool.h>
+#include <tos.h>
 
 #include "arm.h"
 #include "reboot.h"
@@ -24,6 +25,9 @@
 
 enum {
 	Minmem	= 256*MB,			/* conservative default */
+
+	/* space for syscall args, return PC, top-of-stack struct */
+	Ustkheadroom	= sizeof(Sargs) + sizeof(uintptr) + sizeof(Tos),
 };
 
 #define isascii(c) ((uchar)(c) > 0 && (uchar)(c) < 0177)
@@ -714,7 +718,7 @@
 	 * of the argument list checked in syscall.
 	 */
 	i = oargblen+1;
-	p = UINT2PTR(STACKALIGN(base + BY2PG - sizeof(up->s.args) - i));
+	p = UINT2PTR(STACKALIGN(base + BY2PG - Ustkheadroom));
 	memmove(p, oargb, i);
 
 	/*