kbuild: scripts/mkmakefile: dynamic determination of output directory

Rather than fixing the output directory in the generated Makefile,
determine it from the placement of Makefile. This allows moving
the build tree around or accessing it through different mount paths.

(The lastword definition is a compatibility one for make prior to 3.81;
newer make will simply ignore it and use the [faster] built-in.)

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

diff --git a/scripts/mkmakefile b/scripts/mkmakefile
index e0f54b9d8feca95bf693ec7cc9ad294bd70ab1df..e65d8b33faa4cae649044fb48d8fc87fa012d574 100644 (file)
--- a/scripts/mkmakefile
+++ b/scripts/mkmakefile
@@ -25,8 +25,11 @@ cat << EOF > $2/Makefile
 VERSION = $3
 PATCHLEVEL = $4
 
-KERNELSRC    := $1
-KERNELOUTPUT := $2
+lastword = \$(word \$(words \$(1)),\$(1))
+makedir := \$(dir \$(call lastword,\$(MAKEFILE_LIST)))
+
+MAKEARGS := -C $1
+MAKEARGS += O=\$(if \$(patsubst /%,,\$(makedir)),\$(CURDIR)/)\$(patsubst %/,%,\$(makedir))
 
 MAKEFLAGS += --no-print-directory
 
@@ -35,10 +38,11 @@ MAKEFLAGS += --no-print-directory
 all    := \$(filter-out all Makefile,\$(MAKECMDGOALS))
 
 all:
-       \$(MAKE) -C \$(KERNELSRC) O=\$(KERNELOUTPUT) \$(all)
+       \$(MAKE) \$(MAKEARGS) \$(all)
 
 Makefile:;
 
 \$(all) %/: all
        @:
+
 EOF