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 The use of GZIP in gzip tool is obsolete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>

4 files changed, 14 insertions, 14 deletions

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index e598b07e6de4..127f2a7e3ced 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -244,7 +244,7 @@ cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
 # ---------------------------------------------------------------------------
 
 quiet_cmd_gzip = GZIP    $@
-      cmd_gzip = cat $(real-prereqs) | gzip -n -f -9 > $@
+      cmd_gzip = cat $(real-prereqs) | $(_GZIP) -n -f -9 > $@
 
 # DTC
 # ---------------------------------------------------------------------------
@@ -337,19 +337,19 @@ printf "%08x\n" $$dec_size |						\
 )
 
 quiet_cmd_bzip2 = BZIP2   $@
-      cmd_bzip2 = { cat $(real-prereqs) | bzip2 -9; $(size_append); } > $@
+      cmd_bzip2 = { cat $(real-prereqs) | $(_BZIP2) -9; $(size_append); } > $@
 
 # Lzma
 # ---------------------------------------------------------------------------
 
 quiet_cmd_lzma = LZMA    $@
-      cmd_lzma = { cat $(real-prereqs) | lzma -9; $(size_append); } > $@
+      cmd_lzma = { cat $(real-prereqs) | $(LZMA) -9; $(size_append); } > $@
 
 quiet_cmd_lzo = LZO     $@
-      cmd_lzo = { cat $(real-prereqs) | lzop -9; $(size_append); } > $@
+      cmd_lzo = { cat $(real-prereqs) | $(_LZOP) -9; $(size_append); } > $@
 
 quiet_cmd_lz4 = LZ4     $@
-      cmd_lz4 = { cat $(real-prereqs) | lz4c -l -c1 stdin stdout; \
+      cmd_lz4 = { cat $(real-prereqs) | $(LZ4) -l -c1 stdin stdout; \
                   $(size_append); } > $@
 
 # U-Boot mkimage
@@ -396,7 +396,7 @@ quiet_cmd_xzkern = XZKERN  $@
                      $(size_append); } > $@
 
 quiet_cmd_xzmisc = XZMISC  $@
-      cmd_xzmisc = cat $(real-prereqs) | xz --check=crc32 --lzma2=dict=1MiB > $@
+      cmd_xzmisc = cat $(real-prereqs) | $(XZ) --check=crc32 --lzma2=dict=1MiB > $@
 
 # ASM offsets
 # ---------------------------------------------------------------------------
diff --git a/scripts/Makefile.package b/scripts/Makefile.package
index 02135d2671a6..b2b6153af63a 100644
--- a/scripts/Makefile.package
+++ b/scripts/Makefile.package
@@ -45,7 +45,7 @@ if test "$(objtree)" != "$(srctree)"; then \
 	false; \
 fi ; \
 $(srctree)/scripts/setlocalversion --save-scmversion; \
-tar -cz $(RCS_TAR_IGNORE) -f $(2).tar.gz \
+tar -I $(_GZIP) -c $(RCS_TAR_IGNORE) -f $(2).tar.gz \
 	--transform 's:^:$(2)/:S' $(TAR_CONTENT) $(3); \
 rm -f $(objtree)/.scmversion
 
@@ -127,9 +127,9 @@ util/PERF-VERSION-GEN $(CURDIR)/$(perf-tar)/);              \
 tar rf $(perf-tar).tar $(perf-tar)/HEAD $(perf-tar)/PERF-VERSION-FILE; \
 rm -r $(perf-tar);                                                  \
 $(if $(findstring tar-src,$@),,                                     \
-$(if $(findstring bz2,$@),bzip2,                                    \
-$(if $(findstring gz,$@),gzip,                                      \
-$(if $(findstring xz,$@),xz,                                        \
+$(if $(findstring bz2,$@),$(_BZIP2),                                 \
+$(if $(findstring gz,$@),$(_GZIP),                                  \
+$(if $(findstring xz,$@),$(XZ),                                     \
 $(error unknown target $@))))                                       \
 	-f -9 $(perf-tar).tar)
 
diff --git a/scripts/package/buildtar b/scripts/package/buildtar
index 77c7caefede1..ad62c6879622 100755
--- a/scripts/package/buildtar
+++ b/scripts/package/buildtar
@@ -28,15 +28,15 @@ case "${1}" in
 		opts=
 		;;
 	targz-pkg)
-		opts=--gzip
+		opts="-I ${_GZIP}"
 		tarball=${tarball}.gz
 		;;
 	tarbz2-pkg)
-		opts=--bzip2
+		opts="-I ${_BZIP2}"
 		tarball=${tarball}.bz2
 		;;
 	tarxz-pkg)
-		opts=--xz
+		opts="-I ${XZ}"
 		tarball=${tarball}.xz
 		;;
 	*)
diff --git a/scripts/xz_wrap.sh b/scripts/xz_wrap.sh
index 7a2d372f4885..76e9cbcfbeab 100755
--- a/scripts/xz_wrap.sh
+++ b/scripts/xz_wrap.sh
@@ -20,4 +20,4 @@ case $SRCARCH in
 	sparc)          BCJ=--sparc ;;
 esac
 
-exec xz --check=crc32 $BCJ --lzma2=$LZMA2OPTS,dict=32MiB
+exec $XZ --check=crc32 $BCJ --lzma2=$LZMA2OPTS,dict=32MiB