[PATCH] kbuild: support of new KBUILD_FULL_PATH

[Boaz Harrosh <boaz@plexistor.com>]

The commit 9da0763bdd82572be243fcf5161734f11568960f

	kbuild: Use relative path when building in a subdir of the source tree

	When doing make O=<subdir>, use '..' to refer to the source tree. This
	allows for more readable compiler messages, and, more importantly, it
	sets the VPATH to '..', so filenames in WARN_ON() etc. will be shorter.

	Acked-by: Sam Ravnborg <sam@ravnborg.org>
	Signed-off-by: Michal Marek <mmarek@suse.cz>

Broke IDEs and other tools which analyze the make output.
Introduce a new KBUILD_FULL_PATH switch to Makefile that will revert
to the old output if KBUILD_FULL_PATH=1 is specified.
The default is KBUILD_FULL_PATH=0

Signed-off-by: Boaz Harrosh <boaz@plexistor.com>
---
 Documentation/kbuild/kbuild.txt |  9 +++++++++
 Makefile                        | 13 ++++++++-----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 6466704..9133b47 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -77,6 +77,15 @@ Specify the output directory when building the kernel.
 The output directory can also be specified using "O=...".
 Setting "O=..." takes precedence over KBUILD_OUTPUT.
 
+KBUILD_FULL_PATH
+--------------------------------------------------
+Since Linux v3.16-rc1 the Kernel build system prefers to use
+relative paths when supplying file-paths to gcc and other
+tools. This will break IDEs and other environments that would
+parse the gcc output to find files and lines.
+Use KBUILD_FULL_PATH=1 on make command line to revert to old
+way of feeding tools with full-paths.
+
 KBUILD_DEBARCH
 --------------------------------------------------
 For the deb-pkg target, allows overriding the normal heuristics deployed by
diff --git a/Makefile b/Makefile
index 97b2861..51fcebd 100644
--- a/Makefile
+++ b/Makefile
@@ -153,11 +153,14 @@ ifeq ($(KBUILD_SRC),)
         # building in the source tree
         srctree := .
 else
-        ifeq ($(KBUILD_SRC)/,$(dir $(CURDIR)))
-                # building in a subdirectory of the source tree
-                srctree := ..
-        else
-                srctree := $(KBUILD_SRC)
+        srctree := $(KBUILD_SRC)
+
+        # if KBUILD_FULL_PATH=1 then do not use relative path
+	ifneq ($(KBUILD_FULL_PATH), 1)
+                ifeq ($(KBUILD_SRC)/,$(dir $(CURDIR)))
+                        # building in a subdirectory of the source tree
+                        srctree := ..
+                endif
         endif
 endif
 objtree		:= .
-- 
1.9.3