[Patch] Read CONFIG_RD_ variables for initramfs compression

[P J P <ppandit@redhat.com>]

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    Hello Andrew,

When expert configuration option(CONFIG_EXPERT) is enabled, menuconfig offers 
choice of compression algorithm, to compress initial ramfs image. This choice 
is stored into CONFIG_RD_<GZIP/BZIP2/...> variables.

But, usr/Makefile reads from earlier INITRAMFS_COMPRESSION_* variables to set 
the ramfs file extension(.gzip/.bz2/...), which is later(in 
scripts/gen_initramfs_list.sh) used to apply actual compression.

Since none of the INITRAMFS_COMPRESSION_* variables are defined, the resulting 
'usr/initramfs_data.cpio' file remains un-compressed.

The patch attached herein, updates the usr/Makefile to read CONFIG_RD_* 
variables, and also adds support for the Lz4 compression algorithm.

Could you please review it?
==
PS:
IIUC, I think INITRAMFS_COMPRESSION_* variables are not used anywhere at all. 
Though I'm not sure about the EMBEDDED configurations. But if they are not 
used, it could be better to remove their description/references from 
usr/Kconfig and other places.


Thank you.
--
Prasad J Pandit / Red Hat Security Response Team

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From 0304fb400c27227106c1f9a57fe3de13ca03cca2 Mon Sep 17 00:00:00 2001
From: P J P <prasad@redhat.com>
Date: Tue, 15 Oct 2013 19:28:40 +0530
Subject: 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.

Signed-off-by: P J P <prasad@redhat.com>

diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
index b482f16..5761973 100644
--- a/scripts/gen_initramfs_list.sh
+++ b/scripts/gen_initramfs_list.sh
@@ -246,6 +246,7 @@ case "$arg" in
 		echo "$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 "\.lz4$" && compr="lz4 -9 -f"
 		echo "$output_file" | grep -q "\.cpio$" && compr="cat"
 		shift
 		;;
diff --git a/usr/Makefile b/usr/Makefile
index 029ffe6..06ad948 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -7,19 +7,22 @@ PHONY += klibcdirs
 
 
 # Gzip
-suffix_$(CONFIG_INITRAMFS_COMPRESSION_GZIP)   = .gz
+suffix_$(CONFIG_RD_GZIP)   = .gz
 
 # Bzip2
-suffix_$(CONFIG_INITRAMFS_COMPRESSION_BZIP2)  = .bz2
+suffix_$(CONFIG_RD_BZIP2)  = .bz2
 
 # Lzma
-suffix_$(CONFIG_INITRAMFS_COMPRESSION_LZMA)   = .lzma
+suffix_$(CONFIG_RD_LZMA)   = .lzma
 
 # XZ
-suffix_$(CONFIG_INITRAMFS_COMPRESSION_XZ)     = .xz
+suffix_$(CONFIG_RD_XZ)     = .xz
 
 # Lzo
-suffix_$(CONFIG_INITRAMFS_COMPRESSION_LZO)   = .lzo
+suffix_$(CONFIG_RD_LZO)    = .lzo
+
+# Lz4
+suffix_$(CONFIG_RD_LZ4)    = .lz4
 
 AFLAGS_initramfs_data.o += -DINITRAMFS_IMAGE="usr/initramfs_data.cpio$(suffix_y)"
 
@@ -53,7 +56,10 @@ endif
 quiet_cmd_initfs = GEN     $@
       cmd_initfs = $(initramfs) -o $@ $(ramfs-args) $(ramfs-input)
 
-targets := initramfs_data.cpio.gz initramfs_data.cpio.bz2 initramfs_data.cpio.lzma initramfs_data.cpio.xz initramfs_data.cpio.lzo initramfs_data.cpio
+targets := initramfs_data.cpio.gz initramfs_data.cpio.bz2 \
+	initramfs_data.cpio.lzma initramfs_data.cpio.xz \
+	initramfs_data.cpio.lzo initramfs_data.cpio.lz4 \
+	initramfs_data.cpio
 # do not try to update files included in initramfs
 $(deps_initramfs): ;
 
@@ -66,4 +72,3 @@ $(deps_initramfs): klibcdirs
 $(obj)/initramfs_data.cpio$(suffix_y): $(obj)/gen_init_cpio $(deps_initramfs) klibcdirs
 	$(Q)$(initramfs) -l $(ramfs-input) > $(obj)/.initramfs_data.cpio.d
 	$(call if_changed,initfs)
-
-- 
1.8.3.1