kbuild: fix building external modules

kbuild failed to locate Makefile for external modules.
This brought to my attention how the variables for directories
have different values in different usage scenarios.

Different kbuild usage scenarios:
make       - plain make in same directory where kernel source lives
make O=    - kbuild is told to store output files in another directory
make M=    - building an external module
make O= M= - building an external module with kernel output seperate from src

Value assigned to the different variables:

           |$(src)          |$(obj) |$(srctree)        |$(objtree)
make       |reldir to k src |as src |abs path to k src |abs path to k src
make O=    |reldir to k src |as src |abs path to k src |abs path to output dir
make M=    |abs path to src |as src |abs path to k src |abs path to k src
make O= M= |abs path to src |as src |abs path to k src |abs path to k output

path to kbuild file:

make       | $(srctree)/$(src), $(src)
make O=    | $(srctree)/$(src)
make M=    | $(src)
make O= M= | $(src)

From the table above it can be seen that the only good way to find the
home directory of the kbuild file is to locate the one of the two variants
that is an absolute path. If $(src) is an absolute path (starts with /)
then use it, otherwise prefix $(src) with $(srctree).

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 8f4f5a347767d642307479fea8cd6045b2b50fb9..506e3f3befe3104b35d2518fd42af7fb53048f67 100644 (file)
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -11,8 +11,8 @@ __build:
 -include .config
 
 # The filename Kbuild has precedence over Makefile
-include $(if $(wildcard $(srctree)/$(src)/Kbuild), \
-                        $(srctree)/$(src)/Kbuild, $(srctree)/$(src)/Makefile)
+kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
+include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile)
 
 include scripts/Kbuild.include
 include scripts/Makefile.lib

diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean
index 62351b630fabbec556e0da11779549149036e66a..8974ea5fc878896fac077f274af8a6c60c91568d 100644 (file)
--- a/scripts/Makefile.clean
+++ b/scripts/Makefile.clean
@@ -13,8 +13,8 @@ __clean:
 clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj
 
 # The filename Kbuild has precedence over Makefile
-include $(if $(wildcard $(srctree)/$(src)/Kbuild), \
-                        $(srctree)/$(src)/Kbuild, $(srctree)/$(src)/Makefile)
+kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
+include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile)
 
 # Figure out what we need to build from the various variables
 # ==========================================================================