Re: fastboot: unpacking initramfs faster

[Andreas Robinson <andr345@gmail.com>]

Here is a quick and dirty patch that works for me. Applies to current
git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-x86.git

Work on monolithic-kernel decompression and multithreading is next.

>From 27d64e5fca08d695282da219eb71e5fca978a9d2 Mon Sep 17 00:00:00 2001
From: Andreas Robinson <andr345@gmail.com>
Date: Thu, 26 Mar 2009 16:44:14 +0100
Subject: [PATCH] lib: support lzo-compressed initramfs images

Impact: Allows faster unpacking of the initial ramdisk.

LZO files are marginally larger than gzip, about 7% for the
best compression method lzo1x_999, but decompress about 30%
faster on x86 hardware.

This patch supports a new stream format generated by a
userspace tool named blzo.

Patch content:
* necessary additions to Kconfig and makefiles
* a simple initramfs decompressor
---
 include/linux/decompress/ublzo.h |   12 ++++++
 lib/Kconfig                      |    4 ++
 lib/Makefile                     |    1 +
 lib/decompress.c                 |    5 +++
 lib/decompress_ublzo.c           |   75 ++++++++++++++++++++++++++++++++++++++
 usr/Kconfig                      |    9 +++++
 6 files changed, 106 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/decompress/ublzo.h
 create mode 100644 lib/decompress_ublzo.c

diff --git a/include/linux/decompress/ublzo.h b/include/linux/decompress/ublzo.h
new file mode 100644
index 0000000..e453d07
--- /dev/null
+++ b/include/linux/decompress/ublzo.h
@@ -0,0 +1,12 @@
+#ifndef DECOMPRESS_UBLZO_H
+#define DECOMPRESS_UBLZO_H
+
+int ublzo(unsigned char *, int,
+	  int(*fill)(void*, unsigned int),
+	  int(*flush)(void*, unsigned int),
+	  unsigned char *output,
+	  int *posp,
+	  void(*error)(char *x)
+	);
+
+#endif
diff --git a/lib/Kconfig b/lib/Kconfig
index e3b7d7a..9e5c7f1 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -104,6 +104,10 @@ config LZO_DECOMPRESS
 # These all provide a common interface (hence the apparent duplication with
 # ZLIB_INFLATE; DECOMPRESS_GZIP is just a wrapper.)
 #
+config DECOMPRESS_BLZO
+	select LZO_DECOMPRESS
+	tristate
+
 config DECOMPRESS_GZIP
 	select ZLIB_INFLATE
 	tristate
diff --git a/lib/Makefile b/lib/Makefile
index b24222c..9ee48e8 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_REED_SOLOMON) += reed_solomon/
 obj-$(CONFIG_LZO_COMPRESS) += lzo/
 obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
 
+lib-$(CONFIG_DECOMPRESS_BLZO) += decompress_ublzo.o
 lib-$(CONFIG_DECOMPRESS_GZIP) += decompress_inflate.o
 lib-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o
 lib-$(CONFIG_DECOMPRESS_LZMA) += decompress_unlzma.o
diff --git a/lib/decompress.c b/lib/decompress.c
index d2842f5..8c189a0 100644
--- a/lib/decompress.c
+++ b/lib/decompress.c
@@ -9,10 +9,14 @@
 #include <linux/decompress/bunzip2.h>
 #include <linux/decompress/unlzma.h>
 #include <linux/decompress/inflate.h>
+#include <linux/decompress/ublzo.h>
 
 #include <linux/types.h>
 #include <linux/string.h>
 
+#ifndef CONFIG_DECOMPRESS_BLZO
+# define ublzo NULL
+#endif
 #ifndef CONFIG_DECOMPRESS_GZIP
 # define gunzip NULL
 #endif
@@ -28,6 +32,7 @@ static const struct compress_format {
 	const char *name;
 	decompress_fn decompressor;
 } compressed_formats[] = {
+	{ {'B', 'L'}, "blzo", ublzo },
 	{ {037, 0213}, "gzip", gunzip },
 	{ {037, 0236}, "gzip", gunzip },
 	{ {0x42, 0x5a}, "bzip2", bunzip2 },
diff --git a/lib/decompress_ublzo.c b/lib/decompress_ublzo.c
new file mode 100644
index 0000000..136f57f
--- /dev/null
+++ b/lib/decompress_ublzo.c
@@ -0,0 +1,75 @@
+/* Simple LZO file format decompressor.
+ *
+ *     Copyright (C) 2009 Andreas Robinson <andr345@gmail.com>
+ *
+ *
+ * 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 <linux/types.h>
+#include <linux/lzo.h>
+
+#ifndef STATIC
+#include <linux/decompress/ublzo.h>
+#endif /* STATIC */
+#include <linux/decompress/mm.h>
+
+#define BLZO_BLOCK_SIZE 65536
+
+int INIT ublzo(unsigned char *inbuf, int len,
+		int(*fill)(void*, unsigned int),
+		int(*flush)(void*, unsigned int),
+		unsigned char *output,
+		int *posp,
+		void(*error)(char *x))
+{
+	int ret = LZO_E_OK;
+	size_t start_len, in_len, out_len;
+	void *out;
+
+	start_len = len;
+
+	if (fill) {
+		error("the decompress 'fill' feature is not yet implemented");
+		return LZO_E_ERROR;
+	} else {
+		out = malloc(BLZO_BLOCK_SIZE);
+		if (!out)
+			panic("Cannot allocate decompression buffers!");
+
+		if (memcmp("BLZO", inbuf, 4) != 0)
+			return LZO_E_ERROR;
+
+		inbuf += 4;
+		len -= 4;
+
+		while (len > 0) {
+			in_len = (inbuf[0] << 8) + inbuf[1];
+			inbuf += 2;
+			len -= 2;
+			if (in_len == 0)
+				goto done;
+
+			out_len = BLZO_BLOCK_SIZE;
+			ret = lzo1x_decompress_safe(inbuf, in_len, out, &out_len);
+			if (ret != LZO_E_OK) {
+				error("error in LZO archive");
+				goto done;
+			}
+
+			inbuf += in_len;
+			len -= in_len;
+			flush(out, out_len);
+		}
+	}
+
+done:
+	free(out);
+	*posp = start_len - len;
+	return ret;
+}
+
+#define decompress ublzo
diff --git a/usr/Kconfig b/usr/Kconfig
index 43a3a0f..ff2b15c 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -45,6 +45,15 @@ config INITRAMFS_ROOT_GID
 
 	  If you are not sure, leave it set to "0".
 
+config RD_BLZO
+	bool "Initial ramdisk compressed using blzo"
+	default y
+	depends on BLK_DEV_INITRD=y
+	select DECOMPRESS_BLZO
+	help
+	  Support loading of a blzo encoded initial ramdisk or cpio buffer.
+	  If unsure, say Y.
+
 config RD_GZIP
 	bool "Initial ramdisk compressed using gzip"
 	default y
-- 
1.5.6.3