[PATCH 5.4 038/191] dtc: Use pkg-config to locate libyaml

From: Greg Kroah-Hartman
Date: Thu Jan 02 2020 - 18:00:16 EST

From: Pavel Modilaynen <pavel.modilaynen@xxxxxxxx>

[ Upstream commit 067c650c456e758f933aaf87a202f841d34be269 ]

Using Makefile's wildcard with absolute path to detect
the presence of libyaml results in false-positive
detection when cross-compiling e.g. in yocto environment.
The latter results in build error:
| scripts/dtc/yamltree.o: In function `yaml_propval_int':
| yamltree.c: undefined reference to `yaml_sequence_start_event_initialize'
| yamltree.c: undefined reference to `yaml_emitter_emit'
| yamltree.c: undefined reference to `yaml_scalar_event_initialize'
Use pkg-config to locate libyaml to address this scenario.

Signed-off-by: Pavel Modilaynen <pavel.modilaynen@xxxxxxxx>
[robh: silence stderr]
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
scripts/dtc/Makefile | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
index 82160808765c..b5a5b1c548c9 100644
--- a/scripts/dtc/Makefile
+++ b/scripts/dtc/Makefile
@@ -11,7 +11,7 @@ dtc-objs += dtc-lexer.lex.o dtc-parser.tab.o
# Source files need to get at the userspace version of libfdt_env.h to compile
HOST_EXTRACFLAGS := -I $(srctree)/$(src)/libfdt

-ifeq ($(wildcard /usr/include/yaml.h),)
+ifeq ($(shell pkg-config --exists yaml-0.1 2>/dev/null && echo yes),)
ifneq ($(CHECK_DTBS),)
$(error dtc needs libyaml for DT schema validation support. \
Install the necessary libyaml development package.)
@@ -19,7 +19,7 @@ endif
dtc-objs += yamltree.o
-HOSTLDLIBS_dtc := -lyaml
+HOSTLDLIBS_dtc := $(shell pkg-config yaml-0.1 --libs)

# Generated files need one more search path to include headers in source tree