kbuild: add PYTHON2 and PYTHON3 variables
The variable 'PYTHON' allows users to specify a proper executable
name in case the default 'python' does not work. However, this does
not address the case where both Python 2.x and 3.x scripts are used
in one source tree.
PEP 394 (https://www.python.org/dev/peps/pep-0394/) provides a
convention for Python scripts portability. Here is a quotation:
In order to tolerate differences across platforms, all new code
that needs to invoke the Python interpreter should not specify
'python', but rather should specify either 'python2' or 'python3'.
This distinction should be made in shebangs, when invoking from a
shell script, when invoking via the system() call, or when invoking
in any other context.
One exception to this is scripts that are deliberately written to
be source compatible with both Python 2.x and 3.x. Such scripts may
continue to use python on their shebang line without affecting their
portability.
To meet this requirement, this commit adds new variables 'PYTHON2'
and 'PYTHON3'.
arch/ia64/scripts/unwcheck.py is the only script that has ever used
$(PYTHON). Recent commit bd5edbe67794 ("ia64: convert unwcheck.py to
python3") converted it to be compatible with both Python 2.x and 3.x,
so this is the exceptional case where the use of 'python' is allowed.
So, I did not touch arch/ia64/Makefile.
tools/perf/Makefile.config sets PYTHON and PYTHON2 by itself, so it
is not affected by this commit.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/Makefile b/Makefile
index 5675aa1..de2c8f7 100644
--- a/Makefile
+++ b/Makefile
@@ -385,6 +385,8 @@
DEPMOD = /sbin/depmod
PERL = perl
PYTHON = python
+PYTHON2 = python2
+PYTHON3 = python3
CHECK = sparse
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
@@ -430,7 +432,7 @@
export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
export CPP AR NM STRIP OBJCOPY OBJDUMP HOSTLDFLAGS HOST_LOADLIBES
-export MAKE LEX YACC AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
+export MAKE LEX YACC AWK GENKSYMS INSTALLKERNEL PERL PYTHON PYTHON2 PYTHON3 UTS_MACHINE
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS