[PATCH] kbuild: really fix bzImage build with non-bash sh

[Jonathan Nieder <jrnieder@gmail.com>]

In an x86 build with CONFIG_KERNEL_LZMA enabled and dash as sh,
arch/x86/boot/compressed/vmlinux.bin.lzma ends with
'\xf0\x7d\x39\x00' (16 bytes) instead of the 4 bytes intended and
the resulting vmlinuz fails to boot.  This improves on the
previous behavior, in which the file contained the characters
'-ne ' as well, but not by much.

Previous commits replaced "echo -ne" first with "/bin/echo -ne",
then "printf" in the hope of improving portability, but none of
these commands is guaranteed to support hexadecimal escapes on
POSIX systems.  So use the shell to convert from hexadecimal to
octal.

With this change, an LZMA-compressed kernel built with dash as sh
boots correctly again.

Reported-by: sd@sedf.de
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Michael Tokarev <mjt@tls.msk.ru>
Cc: Alek Du <alek.du@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
Andrew Morton wrote:

> switched to email.

Thanks.

sd@sedf.de reported through <http://bugzilla.kernel.org/show_bug.cgi?id=14848>:

>> The kernel fails to boot if compressed with bzip2 or lzma, gzip works.
>> 
>> Commit 4a2ff67c88211026afcbdbc190c13f705dae1b59 does:

Thanks for tracking it down.  The change below works here.

 scripts/Makefile.lib |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index cd815ac..eabedbb 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -219,8 +219,13 @@ for F in $1; do								\
 	fsize=$$(stat -c "%s" $$F);					\
 	dec_size=$$(expr $$dec_size + $$fsize);				\
 done;									\
-printf "%08x" $$dec_size |						\
-	sed 's/\(..\)\(..\)\(..\)\(..\)/\\\\x\4\\\\x\3\\\\x\2\\\\x\1/g'	\
+printf "%08x\n" $$dec_size |						\
+	sed 's/\(..\)/\1 /g' | {					\
+		read ch0 ch1 ch2 ch3;					\
+		for ch in $$ch3 $$ch2 $$ch1 $$ch0; do			\
+			printf '%s%03o' '\\' $$((0x$$ch)); 		\
+		done;							\
+	}								\
 )
 
 quiet_cmd_bzip2 = BZIP2   $@
-- 
1.6.5.7