kbuild: add variables for compression tools
authorDenis Efremov <efremov@linux.com>
Fri, 5 Jun 2020 07:39:55 +0000 (10:39 +0300)
committerMasahiro Yamada <masahiroy@kernel.org>
Sat, 6 Jun 2020 14:42:01 +0000 (23:42 +0900)
commit8dfb61dcbaceb19a5ded5e9c9dcf8d05acc32294
treee533bf8292cb5973d7e21318690d417d83bcf679
parente0b250b57dcf403529081e5898a9de717f96b76b
kbuild: add variables for compression tools

Allow user to use alternative implementations of compression tools,
such as pigz, pbzip2, pxz. For example, multi-threaded tools to
speed up the build:
$ make GZIP=pigz BZIP2=pbzip2

Variables _GZIP, _BZIP2, _LZOP are used internally because original env
vars are reserved by the tools. The use of GZIP in gzip tool is obsolete
since 2015. However, alternative implementations (e.g., pigz) still rely
on it. BZIP2, BZIP, LZOP vars are not obsolescent.

The credit goes to @grsecurity.

As a sidenote, for multi-threaded lzma, xz compression one can use:
$ export XZ_OPT="--threads=0"

Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Makefile
arch/arm/boot/deflate_xip_data.sh
arch/ia64/Makefile
arch/m68k/Makefile
arch/parisc/Makefile
kernel/gen_kheaders.sh
scripts/Makefile.lib
scripts/Makefile.package
scripts/package/buildtar
scripts/xz_wrap.sh