initramfs: read CONFIG_RD_ variables for initramfs compression

When expert configuration option(CONFIG_EXPERT) is enabled, menuconfig
offers a choice of compression algorithm to compress initial ramfs image;
This choice is stored into CONFIG_RD_* variables.  But usr/Makefile uses
earlier INITRAMFS_COMPRESSION_* macros to build initial ramfs file.  Since
none of them is defined, resulting 'initramfs_data.cpio' file remains
un-compressed.

This patch updates the Makefile to use CONFIG_RD_* variables and adds
support for LZ4 compression algorithm.  Also updates the
'gen_initramfs_list.sh' script to check whether a selected compression
command is accessible or not.  And fall-back to default gzip(1)
compression when it is not.

Signed-off-by: P J P <prasad@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 18 insertions, 6 deletions

diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
index b482f162a18a..ef474098d9f1 100644
--- a/scripts/gen_initramfs_list.sh
+++ b/scripts/gen_initramfs_list.sh
@@ -240,12 +240,24 @@ case "$arg" in
                 output_file="$1"
                 cpio_list="$(mktemp ${TMPDIR:-/tmp}/cpiolist.XXXXXX)"
                 output=${cpio_list}
-                echo "$output_file" | grep -q "\.gz$" && compr="gzip -n -9 -f"
-                echo "$output_file" | grep -q "\.bz2$" && compr="bzip2 -9 -f"
-                echo "$output_file" | grep -q "\.lzma$" && compr="lzma -9 -f"
-                echo "$output_file" | grep -q "\.xz$" && \
-                                compr="xz --check=crc32 --lzma2=dict=1MiB"
-                echo "$output_file" | grep -q "\.lzo$" && compr="lzop -9 -f"
+                echo "$output_file" | grep -q "\.gz$" \
+                && [ -x "`which gzip 2> /dev/null`" ] \
+                && compr="gzip -n -9 -f"
+                echo "$output_file" | grep -q "\.bz2$" \
+                && [ -x "`which bzip2 2> /dev/null`" ] \
+                && compr="bzip2 -9 -f"
+                echo "$output_file" | grep -q "\.lzma$" \
+                && [ -x "`which lzma 2> /dev/null`" ] \
+                && compr="lzma -9 -f"
+                echo "$output_file" | grep -q "\.xz$" \
+                && [ -x "`which xz 2> /dev/null`" ] \
+                && compr="xz --check=crc32 --lzma2=dict=1MiB"
+                echo "$output_file" | grep -q "\.lzo$" \
+                && [ -x "`which lzop 2> /dev/null`" ] \
+                && compr="lzop -9 -f"
+                echo "$output_file" | grep -q "\.lz4$" \
+                && [ -x "`which lz4 2> /dev/null`" ] \
+                && compr="lz4 -9 -f"
                 echo "$output_file" | grep -q "\.cpio$" && compr="cat"
                 shift
                 ;;