decompressors: add boot-time XZ support

[cascardo/linux.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index 8dfd094..ea176e8 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -130,13 +130,16 @@ config HAVE_KERNEL_BZIP2
 config HAVE_KERNEL_LZMA
        bool
 
+config HAVE_KERNEL_XZ
+       bool
+
 config HAVE_KERNEL_LZO
        bool
 
 choice
        prompt "Kernel compression mode"
        default KERNEL_GZIP
-       depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_LZO
+       depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
        help
          The linux kernel is a kind of self-extracting executable.
          Several compression algorithms are available, which differ
@@ -181,6 +184,21 @@ config KERNEL_LZMA
          two. Compression is slowest.  The kernel size is about 33%
          smaller with LZMA in comparison to gzip.
 
+config KERNEL_XZ
+       bool "XZ"
+       depends on HAVE_KERNEL_XZ
+       help
+         XZ uses the LZMA2 algorithm and instruction set specific
+         BCJ filters which can improve compression ratio of executable
+         code. The size of the kernel is about 30% smaller with XZ in
+         comparison to gzip. On architectures for which there is a BCJ
+         filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
+         will create a few percent smaller kernel than plain LZMA.
+
+         The speed is about the same as with LZMA: The decompression
+         speed of XZ is better than that of bzip2 but worse than gzip
+         and LZO. Compression is slow.
+
 config KERNEL_LZO
        bool "LZO"
        depends on HAVE_KERNEL_LZO