Add LZO compression support for initramfs and old-style initrd

Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Tested-by: Wu Zhangjin <wuzhangjin@gmail.com>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Russell King <rmk@arm.linux.org.uk>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 31 insertions, 5 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index 1cfe51628e1b..97b136ff117e 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -117,6 +117,10 @@ config DECOMPRESS_BZIP2
 config DECOMPRESS_LZMA
         tristate
 
+config DECOMPRESS_LZO
+        select LZO_DECOMPRESS
+        tristate
+
 #
 # Generic allocator support is selected if needed
 #
diff --git a/lib/Makefile b/lib/Makefile
index 347ad8db29d3..911b25aed1e7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
 lib-$(CONFIG_DECOMPRESS_GZIP) += decompress_inflate.o
 lib-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o
 lib-$(CONFIG_DECOMPRESS_LZMA) += decompress_unlzma.o
+lib-$(CONFIG_DECOMPRESS_LZO) += decompress_unlzo.o
 
 obj-$(CONFIG_TEXTSEARCH) += textsearch.o
 obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o
diff --git a/lib/decompress.c b/lib/decompress.c
index d2842f571674..a7606815541f 100644
--- a/lib/decompress.c
+++ b/lib/decompress.c
@@ -9,6 +9,7 @@
 #include <linux/decompress/bunzip2.h>
 #include <linux/decompress/unlzma.h>
 #include <linux/decompress/inflate.h>
+#include <linux/decompress/unlzo.h>
 
 #include <linux/types.h>
 #include <linux/string.h>
@@ -22,6 +23,9 @@
 #ifndef CONFIG_DECOMPRESS_LZMA
 # define unlzma NULL
 #endif
+#ifndef CONFIG_DECOMPRESS_LZO
+# define unlzo NULL
+#endif
 
 static const struct compress_format {
         unsigned char magic[2];
@@ -32,6 +36,7 @@ static const struct compress_format {
         { {037, 0236}, "gzip", gunzip },
         { {0x42, 0x5a}, "bzip2", bunzip2 },
         { {0x5d, 0x00}, "lzma", unlzma },
+        { {0x89, 0x4c}, "lzo", unlzo },
         { {0, 0}, NULL, NULL }
 };
 
diff --git a/usr/Kconfig b/usr/Kconfig
index 1c3039f28909..e2721f5a3504 100644
--- a/usr/Kconfig
+++ b/usr/Kconfig
@@ -72,6 +72,15 @@ config RD_LZMA
           Support loading of a LZMA encoded initial ramdisk or cpio buffer
           If unsure, say N.
 
+config RD_LZO
+        bool "Support initial ramdisks compressed using LZO" if EMBEDDED
+        default !EMBEDDED
+        depends on BLK_DEV_INITRD
+        select DECOMPRESS_LZO
+        help
+          Support loading of a LZO encoded initial ramdisk or cpio buffer
+          If unsure, say N.
+
 choice
         prompt "Built-in initramfs compression mode" if INITRAMFS_SOURCE!=""
         help
@@ -108,16 +117,15 @@ config INITRAMFS_COMPRESSION_GZIP
         bool "Gzip"
         depends on RD_GZIP
         help
-          The old and tried gzip compression. Its compression ratio is
-          the poorest among the 3 choices; however its speed (both
-          compression and decompression) is the fastest.
+          The old and tried gzip compression. It provides a good balance
+          between compression ratio and decompression speed.
 
 config INITRAMFS_COMPRESSION_BZIP2
         bool "Bzip2"
         depends on RD_BZIP2
         help
           Its compression ratio and speed is intermediate.
-          Decompression speed is slowest among the three.  The initramfs
+          Decompression speed is slowest among the four.  The initramfs
           size is about 10% smaller with bzip2, in comparison to gzip.
           Bzip2 uses a large amount of memory. For modern kernels you
           will need at least 8MB RAM or more for booting.
@@ -128,7 +136,15 @@ config INITRAMFS_COMPRESSION_LZMA
         help
           The most recent compression algorithm.
           Its ratio is best, decompression speed is between the other
-          two. Compression is slowest.  The initramfs size is about 33%
+          three. Compression is slowest. The initramfs size is about 33%
           smaller with LZMA in comparison to gzip.
 
+config INITRAMFS_COMPRESSION_LZO
+        bool "LZO"
+        depends on RD_LZO
+        help
+          Its compression ratio is the poorest among the four. The kernel
+          size is about about 10% bigger than gzip; however its speed
+          (both compression and decompression) is the fastest.
+
 endchoice