diff --git a/src/cmd/6l/obj.c b/src/cmd/6l/obj.c
index 0e5dafe9a2..fec3a603f9 100644
--- a/src/cmd/6l/obj.c
+++ b/src/cmd/6l/obj.c
@@ -60,7 +60,7 @@ isobjfile(char *f)
 	n = Bread(b, buf1, 5);
 	if(n == 5 && (buf1[2] == 1 && buf1[3] == '<' || buf1[3] == 1 && buf1[4] == '<'))
 		v = 1;	/* good enough for our purposes */
-	else{
+	else {
 		Bseek(b, 0, 0);
 		n = Bread(b, buf2, SARMAG);
 		v = n == SARMAG && strncmp(buf2, ARMAG, SARMAG) == 0;
@@ -347,22 +347,27 @@ main(int argc, char *argv[])
 	lastp = firstp;
 
 	if(INITENTRY == nil) {
-		INITENTRY = "_rt0";
-		a = mal(strlen(INITENTRY)+strlen(goarch)+strlen(goos)+10);
-		strcpy(a, INITENTRY);
-		strcat(a, "_");
-		strcat(a, goarch);
-		strcat(a, "_");
-		strcat(a, goos);
-		INITENTRY = a;
+		INITENTRY = mal(strlen(goarch)+strlen(goos)+10);
+		sprint(INITENTRY, "_rt0_%s_%s", goarch, goos);
 	}
-
 	lookup(INITENTRY, 0)->type = SXREF;
 
+	if(!debug['l']) {
+		a = mal(strlen(goroot)+strlen(goarch)+strlen(goos)+20);
+		sprint(a, "%s/lib/rt0_%s_%s.6", goroot, goarch, goos);
+		objfile(a);
+	}
+
 	while(*argv)
 		objfile(*argv++);
-	if(!debug['l'])
+
+	if(!debug['l']) {
 		loadlib();
+		a = mal(strlen(goroot)+strlen(goarch)+20);
+		sprint(a, "%s/lib/rt_%s.6", goroot, goarch);
+		objfile(a);
+	}
+
 	firstp = firstp->link;
 	if(firstp == P)
 		errorexit();
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 1d77cc4c4f..4cd88d94db 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -321,6 +321,7 @@ struct	Io
 EXTERN	Io	curio;
 EXTERN	Io	pushedio;
 
+EXTERN	char*	infile;
 EXTERN	char*	outfile;
 EXTERN	char*	package;
 EXTERN	Biobuf*	bout;
diff --git a/src/cmd/gc/lex.c b/src/cmd/gc/lex.c
index d0edaa19c8..2ed4bd63e9 100644
--- a/src/cmd/gc/lex.c
+++ b/src/cmd/gc/lex.c
@@ -49,7 +49,8 @@ mainlex(int argc, char *argv[])
 	
 	lexinit();
 
-	curio.infile = argv[0];
+	infile = argv[0];
+	curio.infile = infile;
 
 	curio.bin = Bopen(curio.infile, OREAD);
 	if(curio.bin == nil)
@@ -1066,6 +1067,7 @@ mkpackage(char* pkg)
 {
 	Sym *s;
 	long h;
+	char *p;
 
 	if(bout != nil) {
 		yyerror("mkpackage: called again %s %s", pkg, package);
@@ -1082,7 +1084,16 @@ mkpackage(char* pkg)
 
 	if(outfile == nil) {
 		// BOTCH need to get .6 from backend
-		snprint(namebuf, sizeof(namebuf), "%s.6", package);
+		p = strrchr(infile, '/');
+		if(p == nil)
+			p = infile;
+		else
+			p = p+1;
+		snprint(namebuf, sizeof(namebuf), "%s", p);
+		p = strrchr(namebuf, '.');
+		if(p != nil)
+			*p = 0;
+		strncat(namebuf, ".6", sizeof(namebuf));
 		outfile = strdup(namebuf);
 	}
 }
diff --git a/src/runtime/make.bash b/src/runtime/make.bash
new file mode 100644
index 0000000000..903607325f
--- /dev/null
+++ b/src/runtime/make.bash
@@ -0,0 +1,14 @@
+# Copyright 2009 The Go Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+set -ex
+
+6a rt0_amd64_darwin.s
+mv rt0_amd64_darwin.6 ../../lib/rt0_amd64_darwin.6
+
+6a rt0_amd64_linux.s
+mv rt0_amd64_linux.6 ../../lib/rt0_amd64_linux.6
+
+6c runtime.c
+mv runtime.6 ../../lib/rt_amd64.6
diff --git a/src/runtime/runtime.c b/src/runtime/runtime.c
new file mode 100644
index 0000000000..c99333ba7b
--- /dev/null
+++ b/src/runtime/runtime.c
@@ -0,0 +1,595 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+
+int32	debug	= 0;
+
+void
+sys_printbool(bool v)
+{
+	if(v) {
+		sys_write(1, (byte*)"true", 4);
+		return;
+	}
+	sys_write(1, (byte*)"false", 5);
+}
+
+void
+sys_printfloat(float64 v)
+{
+	sys_write(1, "printfloat", 10);
+}
+
+void
+sys_printint(int64 v)
+{
+	byte buf[100];
+	int32 i, s;
+
+	s = 0;
+	if(v < 0) {
+		v = -v;
+		s = 1;
+		if(v < 0) {
+			sys_write(1, (byte*)"-oo", 3);
+			return;
+		}
+	}
+
+	for(i=nelem(buf)-1; i>0; i--) {
+		buf[i] = v%10 + '0';
+		if(v < 10)
+			break;
+		v = v/10;
+	}
+	if(s) {
+		i--;
+		buf[i] = '-';
+	}
+	sys_write(1, buf+i, nelem(buf)-i);
+}
+
+void
+sys_printpointer(void *p)
+{
+	uint64 v;
+	byte buf[100];
+	int32 i;
+
+	v = (int64)p;
+	for(i=nelem(buf)-1; i>0; i--) {
+		buf[i] = v%16 + '0';
+		if(buf[i] > '9')
+			buf[i] += 'a'-'0'-10;
+		if(v < 16)
+			break;
+		v = v/16;
+	}
+	sys_write(1, buf+i, nelem(buf)-i);
+}
+
+void
+sys_panicl(int32 lno)
+{
+	prints("\npanic on line ");
+	sys_printint(lno);
+	prints("\n");
+	*(int32*)0 = 0;
+}
+
+void
+sys_printstring(string v)
+{
+	sys_write(1, v->str, v->len);
+}
+
+int32
+strlen(int8 *s)
+{
+	int32 l;
+
+	for(l=0; s[l]!=0; l++)
+		;
+	return l;
+}
+
+void
+prints(int8 *s)
+{
+	sys_write(1, s, strlen(s));
+}
+
+dump(byte *p, int32 n)
+{
+	uint32 v;
+	int32 i;
+
+	for(i=0; i<n; i++) {
+		sys_printpointer((byte*)(p[i]>>4));
+		sys_printpointer((byte*)(p[i]&0xf));
+		if((i&15) == 15)
+			prints("\n");
+		else
+			prints(" ");
+	}
+	if(n & 15)
+		prints("\n");
+}
+
+static	uint8*	hunk;
+static	uint32	nhunk;
+static	uint64	nmmap;
+static	uint64	nmal;
+enum
+{
+	NHUNK		= 20<<20,
+
+	PROT_NONE	= 0x00,
+	PROT_READ	= 0x01,
+	PROT_WRITE	= 0x02,
+	PROT_EXEC	= 0x04,
+
+	MAP_FILE	= 0x0000,
+	MAP_SHARED	= 0x0001,
+	MAP_PRIVATE	= 0x0002,
+	MAP_FIXED	= 0x0010,
+	MAP_ANON	= 0x1000,
+};
+
+static void
+throw(int8 *s)
+{
+	prints("throw: ");
+	prints(s);
+	prints("\n");
+	sys_exit(1);
+}
+
+static void
+mcpy(byte *t, byte *f, uint32 n)
+{
+	while(n > 0) {
+		*t = *f;
+		t++;
+		f++;
+		n--;
+	}
+}
+
+static byte*
+brk(uint32 n)
+{
+	byte* v;
+
+	v = sys_mmap(nil, NHUNK, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0);
+	sys_memclr(v, n);
+	nmmap += n;
+	return v;
+}
+
+static void*
+mal(uint32 n)
+{
+	byte* v;
+
+	// round to keep everything 64-bit alligned
+	while(n & 7)
+		n++;
+
+	nmal += n;
+
+	// do we have enough in contiguous hunk
+	if(n > nhunk) {
+
+		// if it is big allocate it separately
+		if(n > NHUNK)
+			return brk(n);
+
+		// allocate a new contiguous hunk
+		hunk = brk(NHUNK);
+		nhunk = NHUNK;
+	}
+
+	// allocate from the contiguous hunk
+	v = hunk;
+	hunk += n;
+	nhunk -= n;
+	return v;
+}
+
+void
+sys_mal(uint32 n, uint8 *ret)
+{
+	ret = mal(n);
+	FLUSH(&ret);
+}
+
+void
+sys_catstring(string s1, string s2, string s3)
+{
+	uint32 l;
+
+	if(s1->len == 0) {
+		s3 = s2;
+		goto out;
+	}
+	if(s2->len == 0) {
+		s3 = s1;
+		goto out;
+	}
+
+	l = s1->len + s2->len;
+
+	s3 = mal(sizeof(s3->len)+l);
+	s3->len = l;
+	mcpy(s3->str, s1->str, s1->len);
+	mcpy(s3->str+s1->len, s2->str, s2->len);
+
+out:
+	FLUSH(&s3);
+}
+
+void
+sys_cmpstring(string s1, string s2, int32 v)
+{
+	uint32 i, l;
+	byte c1, c2;
+
+	l = s1->len;
+	if(s2->len < l)
+		l = s2->len;
+	for(i=0; i<l; i++) {
+		c1 = s1->str[i];
+		c2 = s2->str[i];
+		if(c1 < c2) {
+			v = -1;
+			goto out;
+		}
+		if(c1 > c2) {
+			v = +1;
+			goto out;
+		}
+	}
+	if(s1->len < s2->len) {
+		v = -1;
+		goto out;
+	}
+	if(s1->len > s2->len) {
+		v = +1;
+		goto out;
+	}
+	v = 0;
+
+out:
+	FLUSH(&v);
+}
+
+static int32
+strcmp(byte *s1, byte *s2)
+{
+	uint32 i;
+	byte c1, c2;
+
+	for(i=0;; i++) {
+		c1 = s1[i];
+		c2 = s2[i];
+		if(c1 < c2)
+			return -1;
+		if(c1 > c2)
+			return +1;
+		if(c1 == 0)
+			return 0;
+	}
+}
+
+static void
+prbounds(int8* s, int32 a, int32 b, int32 c)
+{
+	int32 i;
+
+	prints(s);
+	prints(" ");
+	sys_printint(a);
+	prints("<");
+	sys_printint(b);
+	prints(">");
+	sys_printint(c);
+	prints("\n");
+	throw("bounds");
+}
+
+void
+sys_slicestring(string si, int32 lindex, int32 hindex, string so)
+{
+	string s, str;
+	int32 l;
+
+	if(lindex < 0 || lindex > si->len ||
+	   hindex < lindex || hindex > si->len)
+		prbounds("slice", lindex, si->len, hindex);
+
+	l = hindex-lindex;
+	so = mal(sizeof(so->len)+l);
+	so->len = l;
+	mcpy(so->str, si->str+lindex, l);
+	FLUSH(&so);
+}
+
+void
+sys_indexstring(string s, int32 i, byte b)
+{
+	if(i < 0 || i >= s->len)
+		prbounds("index", 0, i, s->len);
+
+	b = s->str[i];
+	FLUSH(&b);
+}
+
+/*
+ * this is the plan9 runetochar
+ * extended for 36 bits in 7 bytes
+ * note that it truncates to 32 bits
+ * through the argument passing.
+ */
+static int32
+runetochar(byte *str, uint32 c)
+{
+	int32 i, n;
+	uint32 mask, mark;
+
+	/*
+	 * one character in 7 bits
+	 */
+	if(c <= 0x07FUL) {
+		str[0] = c;
+		return 1;
+	}
+
+	/*
+	 * every new character picks up 5 bits
+	 * one less in the first byte and
+	 * six more in an extension byte
+	 */
+	mask = 0x7ffUL;
+	mark = 0xC0UL;
+	for(n=1;; n++) {
+		if(c <= mask)
+			break;
+		mask = (mask<<5) | 0x1fUL;
+		mark = (mark>>1) | 0x80UL;
+	}
+
+	/*
+	 * lay down the bytes backwards
+	 * n is the number of extension bytes
+	 * mask is the max codepoint
+	 * mark is the zeroth byte indicator
+	 */
+	for(i=n; i>0; i--) {
+		str[i] = 0x80UL | (c&0x3fUL);
+		c >>= 6;
+	}
+
+	str[0] = mark|c;
+	return n+1;
+}
+
+void
+sys_intstring(int64 v, string s)
+{
+	int32 l;
+
+	s = mal(sizeof(s->len)+8);
+	s->len = runetochar(s->str, v);
+	FLUSH(&s);
+}
+
+void
+sys_byteastring(byte *a, int32 l, string s)
+{
+	s = mal(sizeof(s->len)+l);
+	s->len = l;
+	mcpy(s->str, a, l);
+	FLUSH(&s);
+}
+
+static	Map*	hash[1009];
+
+static Map*
+hashmap(Sigi *si, Sigs *ss)
+{
+	int32 ns, ni;
+	uint32 ihash, h;
+	byte *sname, *iname;
+	Map *m;
+
+	h = ((uint32)si + (uint32)ss) % nelem(hash);
+	for(m=hash[h]; m!=nil; m=m->link) {
+		if(m->si == si && m->ss == ss) {
+			if(m->bad) {
+				throw("bad hashmap");
+				m = nil;
+			}
+			// prints("old hashmap\n");
+			return m;
+		}
+	}
+
+	ni = si[0].offset;	// first word has size
+	m = mal(sizeof(*m) + ni*sizeof(m->fun[0]));
+	m->si = si;
+	m->ss = ss;
+
+	ni = 1;			// skip first word
+	ns = 0;
+
+loop1:
+	// pick up next name from
+	// interface signature
+	iname = si[ni].name;
+	if(iname == nil) {
+		m->link = hash[h];
+		hash[h] = m;
+		// prints("new hashmap\n");
+		return m;
+	}
+	ihash = si[ni].hash;
+
+loop2:
+	// pick up and comapre next name
+	// from structure signature
+	sname = ss[ns].name;
+	if(sname == nil) {
+		prints((int8*)iname);
+		prints(": ");
+		throw("hashmap: failed to find method");
+		m->bad = 1;
+		m->link = hash[h];
+		hash[h] = m;
+		return nil;
+	}
+	if(ihash != ss[ns].hash ||
+	   strcmp(sname, iname) != 0) {
+		ns++;
+		goto loop2;
+	}
+
+	m->fun[si[ni].offset] = ss[ns].fun;
+	ni++;
+	goto loop1;
+}
+
+void
+sys_ifaces2i(Sigi *si, Sigs *ss, Map *m, void *s)
+{
+
+	if(debug) {
+		prints("s2i sigi=");
+		sys_printpointer(si);
+		prints(" sigs=");
+		sys_printpointer(ss);
+		prints(" s=");
+		sys_printpointer(s);
+	}
+
+	if(s == nil) {
+		throw("ifaces2i: nil pointer");
+		m = nil;
+		FLUSH(&m);
+		return;
+	}
+
+	m = hashmap(si, ss);
+
+	if(debug) {
+		prints(" returning m=");
+		sys_printpointer(m);
+		prints(" s=");
+		sys_printpointer(s);
+		prints("\n");
+		dump((byte*)m, 64);
+	}
+
+	FLUSH(&m);
+}
+
+void
+sys_ifacei2i(Sigi *si, Map *m, void *s)
+{
+
+	if(debug) {
+		prints("i2i sigi=");
+		sys_printpointer(si);
+		prints(" m=");
+		sys_printpointer(m);
+		prints(" s=");
+		sys_printpointer(s);
+	}
+
+	if(m == nil) {
+		throw("ifacei2i: nil map");
+		s = nil;
+		FLUSH(&s);
+		return;
+	}
+
+	if(m->si == nil) {
+		throw("ifacei2i: nil pointer");
+		return;
+	}
+
+	if(m->si != si) {
+		m = hashmap(si, m->ss);
+		FLUSH(&m);
+	}
+
+	if(debug) {
+		prints(" returning m=");
+		sys_printpointer(m);
+		prints(" s=");
+		sys_printpointer(s);
+		prints("\n");
+		dump((byte*)m, 64);
+	}
+}
+
+void
+sys_ifacei2s(Sigs *ss, Map *m, void *s)
+{
+
+	if(debug) {
+		prints("i2s m=");
+		sys_printpointer(m);
+		prints(" s=");
+		sys_printpointer(s);
+		prints("\n");
+	}
+
+	if(m == nil) {
+		throw("ifacei2s: nil map");
+		s = nil;
+		FLUSH(&s);
+		return;
+	}
+
+	if(m->ss != ss) {
+		dump((byte*)m, 64);
+		throw("ifacei2s: wrong pointer");
+		s = nil;
+		FLUSH(&s);
+		return;
+	}
+}
+
+void
+check(void)
+{
+	int8 a;
+	uint8 b;
+	int16 c;
+	uint16 d;
+	int32 e;
+	uint32 f;
+	int64 g;
+	uint64 h;
+	float32 i;
+	float64 j;
+	void* k;
+	uint16* l;
+
+	if(sizeof(a) != 1) throw("bad a");
+	if(sizeof(b) != 1) throw("bad b");
+	if(sizeof(c) != 2) throw("bad c");
+	if(sizeof(d) != 2) throw("bad d");
+	if(sizeof(e) != 4) throw("bad e");
+	if(sizeof(f) != 4) throw("bad f");
+	if(sizeof(g) != 8) throw("bad g");
+	if(sizeof(h) != 8) throw("bad h");
+	if(sizeof(i) != 4) throw("bad i");
+	if(sizeof(j) != 8) throw("bad j");
+	if(sizeof(k) != 8) throw("bad k");
+	if(sizeof(l) != 8) throw("bad l");
+//	prints(1"check ok\n");
+}
diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h
new file mode 100644
index 0000000000..65c3278e59
--- /dev/null
+++ b/src/runtime/runtime.h
@@ -0,0 +1,107 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+
+/*
+ * basic types
+ */
+typedef	signed char		int8;
+typedef	unsigned char		uint8;
+typedef	signed short		int16;
+typedef	unsigned short		uint16;
+typedef	signed int		int32;
+typedef	unsigned int		uint32;
+typedef	signed long long int	int64;
+typedef	unsigned long long int	uint64;
+typedef	float			float32;
+typedef	double			float64;
+
+/*
+ * get rid of C types
+ */
+#define	unsigned		XXunsigned
+#define	signed			XXsigned
+#define	char			XXchar
+#define	short			XXshort
+#define	int			XXint
+#define	long			XXlong
+#define	float			XXfloat
+#define	double			XXdouble
+
+/*
+ * defined types
+ */
+typedef	uint8			bool;
+typedef	uint8			byte;
+typedef	struct
+{
+	int32	len;
+	byte	str[1];
+}				*string;
+typedef	struct
+{
+	byte*	name;
+	uint32	hash;
+	void	(*fun)(void);
+}				Sigs;
+typedef	struct
+{
+	byte*	name;
+	uint32	hash;
+	uint32	offset;
+}				Sigi;
+typedef	struct	Map		Map;
+struct	Map
+{
+	Sigi*	si;
+	Sigs*	ss;
+	Map*	link;
+	int32	bad;
+	int32	unused;
+	void	(*fun[])(void);
+};
+
+/*
+ * defined constants
+ */
+enum
+{
+	true	= 1,
+	false	= 0,
+};
+
+/*
+ * defined macros
+ *    you need super-goru privilege
+ *    to add this list.
+ */
+#define	nelem(x)	(sizeof(x)/sizeof((x)[0]))
+#define	nil		((void*)0)
+
+/*
+ * very low level
+ */
+void	FLUSH(void*);
+void	prints(int8*);
+void	sys_exit(int32);
+void	sys_write(int32, void*, int32);
+void	sys_breakpoint(void);
+uint8*	sys_mmap(byte*, uint32, int32, int32, int32, uint32);
+void	sys_memclr(byte*, uint32);
+
+/*
+ * runtime
+ */
+void	sys_printbool(bool);
+void	sys_printfloat(float64);
+void	sys_printint(int64);
+void	sys_printstring(string);
+void	sys_catstring(string, string, string);
+void	sys_cmpstring(string, string, int32);
+void	sys_slicestring(string, int32, int32, string);
+void	sys_indexstring(string, int32, byte);
+void	sys_intstring(int64, string);
+void	sys_ifaces2i(Sigi*, Sigs*, Map*, void*);
+void	sys_ifacei2i(Sigi*, Map*, void*);
+void	sys_ifacei2s(Sigs*, Map*, void*);