diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index dc77940..3628d86 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -41,7 +41,8 @@
 		$(addprefix $(obj)/,$(zlibheader))
 
 src-wlib := string.S stdio.c main.c flatdevtree.c flatdevtree_misc.c \
-		ns16550.c serial.c simple_alloc.c div64.S util.S $(zlib)
+		ns16550.c serial.c simple_alloc.c div64.S util.S \
+		gunzip_util.c $(zlib)
 src-plat := of.c
 src-boot := crt0.S $(src-wlib) $(src-plat) empty.c
 
diff --git a/arch/powerpc/boot/gunzip_util.c b/arch/powerpc/boot/gunzip_util.c
new file mode 100644
index 0000000..3d9ff8f
--- /dev/null
+++ b/arch/powerpc/boot/gunzip_util.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright 2007 David Gibson, IBM Corporation.
+ * Based on earlier work, Copyright (C) Paul Mackerras 1997.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <stddef.h>
+#include "string.h"
+#include "stdio.h"
+#include "ops.h"
+#include "gunzip_util.h"
+
+struct gunzip_state state;
+
+#define HEAD_CRC	2
+#define EXTRA_FIELD	4
+#define ORIG_NAME	8
+#define COMMENT		0x10
+#define RESERVED	0xe0
+
+void gunzip_start(struct gunzip_state *state, void *src, int srclen)
+{
+	char *hdr = src;
+	int hdrlen = 0;
+
+	memset(state, 0, sizeof(*state));
+
+	/* Check for gzip magic number */
+	if ((hdr[0] == 0x1f) && (hdr[1] == 0x8b)) {
+		/* gzip data, initialize zlib parameters */
+		int r, flags;
+
+		state->s.workspace = state->scratch;
+		if (zlib_inflate_workspacesize() > sizeof(state->scratch)) {
+			printf("insufficient scratch space for gunzip\n\r");
+			exit();
+		}
+
+		/* skip header */
+		hdrlen = 10;
+		flags = hdr[3];
+		if (hdr[2] != Z_DEFLATED || (flags & RESERVED) != 0) {
+			printf("bad gzipped data\n\r");
+			exit();
+		}
+		if ((flags & EXTRA_FIELD) != 0)
+			hdrlen = 12 + hdr[10] + (hdr[11] << 8);
+		if ((flags & ORIG_NAME) != 0)
+			while (hdr[hdrlen++] != 0)
+				;
+		if ((flags & COMMENT) != 0)
+			while (hdr[hdrlen++] != 0)
+				;
+		if ((flags & HEAD_CRC) != 0)
+			hdrlen += 2;
+		if (hdrlen >= srclen) {
+			printf("gunzip_start: ran out of data in header\n\r");
+			exit();
+		}
+
+		r = zlib_inflateInit2(&state->s, -MAX_WBITS);
+		if (r != Z_OK) {
+			printf("inflateInit2 returned %d\n\r", r);
+			exit();
+		}
+	}
+
+	state->s.next_in = src + hdrlen;
+	state->s.avail_in = srclen - hdrlen;
+}
+
+int gunzip_partial(struct gunzip_state *state, void *dst, int dstlen)
+{
+	int len;
+
+	if (state->s.workspace) {
+		/* gunzipping */
+		int r;
+
+		state->s.next_out = dst;
+		state->s.avail_out = dstlen;
+		r = zlib_inflate(&state->s, Z_FULL_FLUSH);
+		if (r != Z_OK && r != Z_STREAM_END) {
+			printf("inflate returned %d msg: %s\n\r", r, state->s.msg);
+			exit();
+		}
+		len = state->s.next_out - (unsigned char *)dst;
+	} else {
+		/* uncompressed image */
+		len = min(state->s.avail_in, (unsigned)dstlen);
+		memcpy(dst, state->s.next_in, len);
+		state->s.next_in += len;
+		state->s.avail_in -= len;
+	}
+	return len;
+}
+
+void gunzip_exactly(struct gunzip_state *state, void *dst, int dstlen)
+{
+	int len;
+
+	len  = gunzip_partial(state, dst, dstlen);
+	if (len < dstlen) {
+		printf("gunzip_block: ran out of data\n\r");
+		exit();
+	}
+}
+
+void gunzip_discard(struct gunzip_state *state, int len)
+{
+	static char discard_buf[128];
+
+	while (len > sizeof(discard_buf)) {
+		gunzip_exactly(state, discard_buf, sizeof(discard_buf));
+		len -= sizeof(discard_buf);
+	}
+
+	if (len > 0)
+		gunzip_exactly(state, discard_buf, len);
+}
+
+int gunzip_finish(struct gunzip_state *state, void *dst, int dstlen)
+{
+	int len;
+
+	if (state->s.workspace) {
+		len = gunzip_partial(state, dst, dstlen);
+		zlib_inflateEnd(&state->s);
+	} else {
+		/* uncompressed image */
+		len = min(state->s.avail_in, (unsigned)dstlen);
+		memcpy(dst, state->s.next_in, len);
+	}
+
+	return len;
+}
diff --git a/arch/powerpc/boot/gunzip_util.h b/arch/powerpc/boot/gunzip_util.h
new file mode 100644
index 0000000..950f62f
--- /dev/null
+++ b/arch/powerpc/boot/gunzip_util.h
@@ -0,0 +1,30 @@
+/*
+ * Decompression convenience functions
+ *
+ * Copyright 2007 David Gibson, IBM Corporation.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+#ifndef _PPC_BOOT_GUNZIP_UTIL_H_
+#define _PPC_BOOT_GUNZIP_UTIL_H_
+
+#include "zlib.h"
+
+/* scratch space for gunzip; 46912 is from zlib_inflate_workspacesize() */
+#define GUNZIP_SCRATCH_SIZE	46912
+
+struct gunzip_state {
+	z_stream s;
+	char scratch[46912];
+};
+
+void gunzip_start(struct gunzip_state *state, void *src, int srclen);
+int gunzip_partial(struct gunzip_state *state, void *dst, int dstlen);
+void gunzip_exactly(struct gunzip_state *state, void *dst, int len);
+void gunzip_discard(struct gunzip_state *state, int len);
+int gunzip_finish(struct gunzip_state *state, void *dst, int len);
+
+#endif /* _PPC_BOOT_GUNZIP_UTIL_H_ */
+
diff --git a/arch/powerpc/boot/main.c b/arch/powerpc/boot/main.c
index 6f6b50d..404620a 100644
--- a/arch/powerpc/boot/main.c
+++ b/arch/powerpc/boot/main.c
@@ -14,8 +14,8 @@
 #include "page.h"
 #include "string.h"
 #include "stdio.h"
-#include "zlib.h"
 #include "ops.h"
+#include "gunzip_util.h"
 #include "flatdevtree.h"
 
 extern void flush_cache(void *, unsigned long);
@@ -30,6 +30,8 @@
 extern char _dtb_start[];
 extern char _dtb_end[];
 
+static struct gunzip_state gzstate;
+
 struct addr_range {
 	unsigned long addr;
 	unsigned long size;
@@ -42,71 +44,12 @@
 static unsigned long elfoffset;
 static int is_64bit;
 
-/* scratch space for gunzip; 46912 is from zlib_inflate_workspacesize() */
-static char scratch[46912];
 static char elfheader[256];
 
 typedef void (*kernel_entry_t)(unsigned long, unsigned long, void *);
 
 #undef DEBUG
 
-#define HEAD_CRC	2
-#define EXTRA_FIELD	4
-#define ORIG_NAME	8
-#define COMMENT		0x10
-#define RESERVED	0xe0
-
-static void gunzip(void *dst, int dstlen, unsigned char *src, int *lenp)
-{
-	z_stream s;
-	int r, i, flags;
-
-	/* skip header */
-	i = 10;
-	flags = src[3];
-	if (src[2] != Z_DEFLATED || (flags & RESERVED) != 0) {
-		printf("bad gzipped data\n\r");
-		exit();
-	}
-	if ((flags & EXTRA_FIELD) != 0)
-		i = 12 + src[10] + (src[11] << 8);
-	if ((flags & ORIG_NAME) != 0)
-		while (src[i++] != 0)
-			;
-	if ((flags & COMMENT) != 0)
-		while (src[i++] != 0)
-			;
-	if ((flags & HEAD_CRC) != 0)
-		i += 2;
-	if (i >= *lenp) {
-		printf("gunzip: ran out of data in header\n\r");
-		exit();
-	}
-
-	if (zlib_inflate_workspacesize() > sizeof(scratch)) {
-		printf("gunzip needs more mem\n");
-		exit();
-	}
-	memset(&s, 0, sizeof(s));
-	s.workspace = scratch;
-	r = zlib_inflateInit2(&s, -MAX_WBITS);
-	if (r != Z_OK) {
-		printf("inflateInit2 returned %d\n\r", r);
-		exit();
-	}
-	s.next_in = src + i;
-	s.avail_in = *lenp - i;
-	s.next_out = dst;
-	s.avail_out = dstlen;
-	r = zlib_inflate(&s, Z_FULL_FLUSH);
-	if (r != Z_OK && r != Z_STREAM_END) {
-		printf("inflate returned %d msg: %s\n\r", r, s.msg);
-		exit();
-	}
-	*lenp = s.next_out - (unsigned char *) dst;
-	zlib_inflateEnd(&s);
-}
-
 static int is_elf64(void *hdr)
 {
 	Elf64_Ehdr *elf64 = hdr;
@@ -132,8 +75,8 @@
 		return 0;
 
 	elfoffset = (unsigned long)elf64ph->p_offset;
-	vmlinux.size = (unsigned long)elf64ph->p_filesz + elfoffset;
-	vmlinux.memsize = (unsigned long)elf64ph->p_memsz + elfoffset;
+	vmlinux.size = (unsigned long)elf64ph->p_filesz;
+	vmlinux.memsize = (unsigned long)elf64ph->p_memsz;
 
 	is_64bit = 1;
 	return 1;
@@ -164,8 +107,8 @@
 		return 0;
 
 	elfoffset = elf32ph->p_offset;
-	vmlinux.size = elf32ph->p_filesz + elf32ph->p_offset;
-	vmlinux.memsize = elf32ph->p_memsz + elf32ph->p_offset;
+	vmlinux.size = elf32ph->p_filesz;
+	vmlinux.memsize = elf32ph->p_memsz;
 	return 1;
 }
 
@@ -177,13 +120,8 @@
 	vmlinuz.size = (unsigned long)(_vmlinux_end - _vmlinux_start);
 
 	/* gunzip the ELF header of the kernel */
-	if (*(unsigned short *)vmlinuz.addr == 0x1f8b) {
-		len = vmlinuz.size;
-		gunzip(elfheader, sizeof(elfheader),
-				(unsigned char *)vmlinuz.addr, &len);
-	} else
-		memcpy(elfheader, (const void *)vmlinuz.addr,
-		       sizeof(elfheader));
+	gunzip_start(&gzstate, (void *)vmlinuz.addr, vmlinuz.size);
+	gunzip_exactly(&gzstate, elfheader, sizeof(elfheader));
 
 	if (!is_elf64(elfheader) && !is_elf32(elfheader)) {
 		printf("Error: not a valid PPC32 or PPC64 ELF file!\n\r");
@@ -192,10 +130,10 @@
 	if (platform_ops.image_hdr)
 		platform_ops.image_hdr(elfheader);
 
-	/* We need to alloc the memsize plus the file offset since gzip
-	 * will expand the header (file offset), then the kernel, then
-	 * possible rubbish we don't care about. But the kernel bss must
-	 * be claimed (it will be zero'd by the kernel itself)
+	/* We need to alloc the memsize: gzip will expand the kernel
+	 * text/data, then possible rubbish we don't care about. But
+	 * the kernel bss must be claimed (it will be zero'd by the
+	 * kernel itself)
 	 */
 	printf("Allocating 0x%lx bytes for kernel ...\n\r", vmlinux.memsize);
 	vmlinux.addr = (unsigned long)malloc(vmlinux.memsize);
@@ -237,24 +175,13 @@
 	}
 
 	/* Eventually gunzip the kernel */
-	if (*(unsigned short *)vmlinuz.addr == 0x1f8b) {
-		printf("gunzipping (0x%lx <- 0x%lx:0x%0lx)...",
-		       vmlinux.addr, vmlinuz.addr, vmlinuz.addr+vmlinuz.size);
-		len = vmlinuz.size;
-		gunzip((void *)vmlinux.addr, vmlinux.memsize,
-			(unsigned char *)vmlinuz.addr, &len);
-		printf("done 0x%lx bytes\n\r", len);
-	} else {
-		memmove((void *)vmlinux.addr,(void *)vmlinuz.addr,
-			vmlinuz.size);
-	}
-
-	/* Skip over the ELF header */
-#ifdef DEBUG
-	printf("... skipping 0x%lx bytes of ELF header\n\r",
-			elfoffset);
-#endif
-	vmlinux.addr += elfoffset;
+	printf("gunzipping (0x%lx <- 0x%lx:0x%0lx)...",
+	       vmlinux.addr, vmlinuz.addr, vmlinuz.addr+vmlinuz.size);
+	/* discard up to the actual load data */
+	gunzip_discard(&gzstate, elfoffset - sizeof(elfheader));
+	len = gunzip_finish(&gzstate, (void *)vmlinux.addr,
+			    vmlinux.memsize);
+	printf("done 0x%lx bytes\n\r", len);
 
 	flush_cache((void *)vmlinux.addr, vmlinux.size);
 }