Re: Kbuild change breaks the ppc64 build

David Miller
2007-02-08T13:17:11Z

From: Oleg Verych <olecom@flower.upol.cz>
Date: Thu, 8 Feb 2007 13:47:56 +0100

> On Thu, Feb 08, 2007 at 10:10:54PM +1100, Paul Mackerras wrote:
> > Commit 5de043f4bd11a9e0a3e8daec7d1905da575a76b7 breaks the build on
> > 64-bit powerpc because we no longer get the -m64 flag passed to gcc.
> > There is code in arch/powerpc/Makefile which adds (or used to add)
> > -m64 to AS, LD and CC if we are running on a 64-bit machine (which I
> > am) and have a biarch toolchain (which I do). Without -m64, the
> > toolchain assumes 32-bit and all sorts of things break spectacularly.
> >
> > I haven't yet tracked down exactly why this commit has this effect,
> > since I find it takes considerable time and effort to understand
> > Kbuild.
>
> As i have refactored some CC checking code in Kbuild.include, it
> turned, that some versions of `make' after calling nested functions,
> add (or leave) prefix whitespace to result, thus ifeq[0] fails:

That's not it, did you see my fix for this problem posted
already? The issue is the leading spaces on the first
line of the define for checker-shell. Those propagate
into the callers, although they are reduced down to a
single space.

This will give you spaces in the result on any version of
make.

Here is my fix again for your reference.

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 8d7eabf..a1880e8 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -60,16 +60,15 @@ endef
# Usage: option = $(call checker-shell,$(CC)...-o $$OUT,option-ok,otherwise)
# Exit code chooses option. $$OUT is safe location for needless output.
define checker-shell
- $(strip
- $(shell set -e; \
- DIR=$(KBUILD_EXTMOD); \
- cd $${DIR:-$(objtree)}; \
- OUT=$$PWD/.$$$$.null; \
- if $(1) >/dev/null 2>&1; \
- then echo "$(2)"; \
- else echo "$(3)"; \
- fi; \
- rm -f $$OUT))
+$(shell set -e; \
+ DIR=$(KBUILD_EXTMOD); \
+ cd $${DIR:-$(objtree)}; \
+ OUT=$$PWD/.$$$$.null; \
+ if $(1) >/dev/null 2>&1; \
+ then echo "$(2)"; \
+ else echo "$(3)"; \
+ fi; \
+ rm -f $$OUT)
endef

# as-option