Re: [PATCH 6/6] Add LZO compression support for initramfs and old-style initrd

Albin Tonnerre
2009-08-03T16:05:36Z

Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
---

Updated with a missing part of the description for INITRAMFS_COMPRESSION_LZO

lib/Kconfig | 4 ++++
lib/Makefile | 1 +
lib/decompress.c | 5 +++++
usr/Kconfig | 26 +++++++++++++++++++++-----
4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/lib/Kconfig b/lib/Kconfig
index bb1326d..8639349 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 2e78277..cfa4041 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 d2842f5..a760681 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 1c3039f..bf30c32 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 ration 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
--
Albin Tonnerre, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.