[PATCH 1/2] kbuild: use separate commands for generating *.dtb and *.dt.yaml

[PATCH 1/2] kbuild: use separate commands for generating *.dtb and *.dt.yaml

[Masahiro Yamada]

Currently, cmd_dtc takes $(2) to select the target format. The
additional parameter complicates things when it is used with
cmd_and_fixdep and if_changed_rule.

To make it easier to understand, use a separate cmd_dtc_yaml.

One visible change is, 'DTCYAML' is used for the log when compiling
*.dts to *.dt.yaml.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/Makefile.lib | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 4b799737722c..8f9f2abf3d67 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -284,32 +284,37 @@ cmd_dt_S_dtb=						\
 $(obj)/%.dtb.S: $(obj)/%.dtb FORCE
 	$(call if_changed,dt_S_dtb)
 
-quiet_cmd_dtc = DTC     $@
-cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
+__cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
 	$(HOSTCC) -E $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
-	$(DTC) -O $(2) -o $@ -b 0 \
+	$(DTC) -O $(1) -o $@ -b 0 \
 		$(addprefix -i,$(dir $<) $(DTC_INCLUDE)) $(DTC_FLAGS) \
 		-d $(depfile).dtc.tmp $(dtc-tmp) ; \
 	cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
 
+quiet_cmd_dtc = DTC     $@
+      cmd_dtc = $(call __cmd_dtc,dtb)
+
 $(obj)/%.dtb: $(src)/%.dts $(DTC) FORCE
-	$(call if_changed_dep,dtc,dtb)
+	$(call if_changed_dep,dtc)
 
 DT_CHECKER ?= dt-validate
 DT_BINDING_DIR := Documentation/devicetree/bindings
 # DT_TMP_SCHEMA may be overridden from Documentation/devicetree/bindings/Makefile
 DT_TMP_SCHEMA ?= $(objtree)/$(DT_BINDING_DIR)/processed-schema.yaml
 
+quiet_cmd_dtc_yaml = DTCYAML $@
+      cmd_dtc_yaml = $(call __cmd_dtc,yaml)
+
 quiet_cmd_dtb_check =	CHECK   $@
       cmd_dtb_check =	$(DT_CHECKER) -u $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA) $@
 
-define rule_dtc
-	$(call cmd_and_fixdep,dtc,yaml)
+define rule_dtc_yaml
+	$(call cmd_and_fixdep,dtc_yaml)
 	$(call cmd,dtb_check)
 endef
 
 $(obj)/%.dt.yaml: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
-	$(call if_changed_rule,dtc,yaml)
+	$(call if_changed_rule,dtc_yaml)
 
 dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
 
-- 
2.25.1

[PATCH 2/2] scripts/dtc: compile separate dtc-yaml

[Masahiro Yamada]

Marek Behún reported a case where pkg-config fails to detect the
libyaml-dev package, which is presumably a bug of the distro.

Irrespective of that, I am not a big fan of pkg-config in the Makefile
parse stage. The cost of pkg-config is quite small, but it is evaluated
everytime we run make, even when we do 'make mrproper'. This commit
changes the Makefile to not rely on pkg-config at all.

The normal build should not require libyaml-dev while we need to compile
dtc with libyaml for the schema check.

Build two dtc variants:

  scripts/dtc/dtc      for *.dts -> *.dtb
  scripts/dtc/dtc-yaml for *.dts -> *.dt.yaml

'make dtbs_check' or 'make dt_binding_check' without libyaml-dev installed
will fail like this:

  scripts/dtc/yamltree.c:9:10: fatal error: yaml.h: No such file or directory

I hope people will notice what to do.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/Makefile.lib      |  9 +++++----
 scripts/dtc/.gitignore    |  1 +
 scripts/dtc/Makefile      | 28 +++++++++++-----------------
 scripts/dtc/dtc-no-yaml.c |  3 +++
 4 files changed, 20 insertions(+), 21 deletions(-)
 create mode 100644 scripts/dtc/dtc-no-yaml.c

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 8f9f2abf3d67..ca12412304b8 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -246,6 +246,7 @@ quiet_cmd_gzip = GZIP    $@
 # DTC
 # ---------------------------------------------------------------------------
 DTC ?= $(objtree)/scripts/dtc/dtc
+DTC_YAML ?= $(objtree)/scripts/dtc/dtc-yaml
 
 # Disable noisy checks by default
 ifeq ($(findstring 1,$(KBUILD_EXTRA_WARN)),)
@@ -286,13 +287,13 @@ $(obj)/%.dtb.S: $(obj)/%.dtb FORCE
 
 __cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
 	$(HOSTCC) -E $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
-	$(DTC) -O $(1) -o $@ -b 0 \
+	$(1) -O $(2) -o $@ -b 0 \
 		$(addprefix -i,$(dir $<) $(DTC_INCLUDE)) $(DTC_FLAGS) \
 		-d $(depfile).dtc.tmp $(dtc-tmp) ; \
 	cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
 
 quiet_cmd_dtc = DTC     $@
-      cmd_dtc = $(call __cmd_dtc,dtb)
+      cmd_dtc = $(call __cmd_dtc,$(DTC),dtb)
 
 $(obj)/%.dtb: $(src)/%.dts $(DTC) FORCE
 	$(call if_changed_dep,dtc)
@@ -303,7 +304,7 @@ DT_BINDING_DIR := Documentation/devicetree/bindings
 DT_TMP_SCHEMA ?= $(objtree)/$(DT_BINDING_DIR)/processed-schema.yaml
 
 quiet_cmd_dtc_yaml = DTCYAML $@
-      cmd_dtc_yaml = $(call __cmd_dtc,yaml)
+      cmd_dtc_yaml = $(call __cmd_dtc,$(DTC_YAML),yaml)
 
 quiet_cmd_dtb_check =	CHECK   $@
       cmd_dtb_check =	$(DT_CHECKER) -u $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA) $@
@@ -313,7 +314,7 @@ define rule_dtc_yaml
 	$(call cmd,dtb_check)
 endef
 
-$(obj)/%.dt.yaml: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
+$(obj)/%.dt.yaml: $(src)/%.dts $(DTC_YAML) $(DT_TMP_SCHEMA) FORCE
 	$(call if_changed_rule,dtc_yaml)
 
 dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
diff --git a/scripts/dtc/.gitignore b/scripts/dtc/.gitignore
index b814e6076bdb..e0cf8222c137 100644
--- a/scripts/dtc/.gitignore
+++ b/scripts/dtc/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
 dtc
+dtc-yaml
diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
index ef85f8b7d4a7..c6d7e2b70f08 100644
--- a/scripts/dtc/Makefile
+++ b/scripts/dtc/Makefile
@@ -1,28 +1,22 @@
 # SPDX-License-Identifier: GPL-2.0
 # scripts/dtc makefile
 
-hostprogs			:= dtc
-always-$(CONFIG_DTC)		+= $(hostprogs)
-always-$(CHECK_DT_BINDING)	+= $(hostprogs)
+# Build the yaml variant for DT schema validation, which requires libyaml
+# development package. The normal build does not need it.
+hostprogs			:= dtc dtc-yaml
+always-$(CONFIG_DTC)		+= dtc
+always-$(CHECK_DTBS)		+= dtc-yaml
+always-$(CHECK_DT_BINDING)	+= dtc-yaml
 
-dtc-objs	:= dtc.o flattree.o fstree.o data.o livetree.o treesource.o \
-		   srcpos.o checks.o util.o
-dtc-objs	+= dtc-lexer.lex.o dtc-parser.tab.o
+common-objs	:= flattree.o fstree.o data.o livetree.o treesource.o \
+		   srcpos.o checks.o util.o dtc-lexer.lex.o dtc-parser.tab.o
+dtc-objs	:= dtc-no-yaml.o $(common-objs)
+dtc-yaml-objs	:= dtc.o yamltree.o $(common-objs)
+HOSTLDLIBS_dtc-yaml := -lyaml
 
 # Source files need to get at the userspace version of libfdt_env.h to compile
 HOST_EXTRACFLAGS := -I $(srctree)/$(src)/libfdt
 
-ifeq ($(shell pkg-config --exists yaml-0.1 2>/dev/null && echo yes),)
-ifneq ($(CHECK_DT_BINDING)$(CHECK_DTBS),)
-$(error dtc needs libyaml for DT schema validation support. \
-	Install the necessary libyaml development package.)
-endif
-HOST_EXTRACFLAGS += -DNO_YAML
-else
-dtc-objs	+= yamltree.o
-HOSTLDLIBS_dtc	:= $(shell pkg-config yaml-0.1 --libs)
-endif
-
 # Generated files need one more search path to include headers in source tree
 HOSTCFLAGS_dtc-lexer.lex.o := -I $(srctree)/$(src)
 HOSTCFLAGS_dtc-parser.tab.o := -I $(srctree)/$(src)
diff --git a/scripts/dtc/dtc-no-yaml.c b/scripts/dtc/dtc-no-yaml.c
new file mode 100644
index 000000000000..f3459e45835f
--- /dev/null
+++ b/scripts/dtc/dtc-no-yaml.c
@@ -0,0 +1,3 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#define NO_YAML
+#include "dtc.c"
-- 
2.25.1

Re: [PATCH 2/2] scripts/dtc: compile separate dtc-yaml

[Rob Herring]

On Sun, May 3, 2020 at 9:07 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Marek Behún reported a case where pkg-config fails to detect the
> libyaml-dev package, which is presumably a bug of the distro.
>
> Irrespective of that, I am not a big fan of pkg-config in the Makefile
> parse stage. The cost of pkg-config is quite small, but it is evaluated
> everytime we run make, even when we do 'make mrproper'. This commit
> changes the Makefile to not rely on pkg-config at all.

I don't really love the solution here... I'm inclined to just make
libyaml always required. Anyone building dtbs should care about
validating them. However, there's some dts files sprinkled in the tree
such as DT unittests and I don't want to break allmodconfig for CI,
0-day, etc. Though eventually we may have to.

> The normal build should not require libyaml-dev while we need to compile
> dtc with libyaml for the schema check.
>
> Build two dtc variants:
>
>   scripts/dtc/dtc      for *.dts -> *.dtb
>   scripts/dtc/dtc-yaml for *.dts -> *.dt.yaml

My longer term plan is to integrate the schema checks into dtc. This
would be some sort of plugin to dtc found or specified at run-time. It
would eliminate the need for 2 passes of dtc and the 2nd case will go
away.

> 'make dtbs_check' or 'make dt_binding_check' without libyaml-dev installed
> will fail like this:
>
>   scripts/dtc/yamltree.c:9:10: fatal error: yaml.h: No such file or directory
>
> I hope people will notice what to do.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
>  scripts/Makefile.lib      |  9 +++++----
>  scripts/dtc/.gitignore    |  1 +
>  scripts/dtc/Makefile      | 28 +++++++++++-----------------
>  scripts/dtc/dtc-no-yaml.c |  3 +++
>  4 files changed, 20 insertions(+), 21 deletions(-)
>  create mode 100644 scripts/dtc/dtc-no-yaml.c
>
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 8f9f2abf3d67..ca12412304b8 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -246,6 +246,7 @@ quiet_cmd_gzip = GZIP    $@
>  # DTC
>  # ---------------------------------------------------------------------------
>  DTC ?= $(objtree)/scripts/dtc/dtc
> +DTC_YAML ?= $(objtree)/scripts/dtc/dtc-yaml

Can we make 'DTC' override both and keep this an internal detail.

>  # Disable noisy checks by default
>  ifeq ($(findstring 1,$(KBUILD_EXTRA_WARN)),)
> @@ -286,13 +287,13 @@ $(obj)/%.dtb.S: $(obj)/%.dtb FORCE
>
>  __cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>         $(HOSTCC) -E $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
> -       $(DTC) -O $(1) -o $@ -b 0 \
> +       $(1) -O $(2) -o $@ -b 0 \
>                 $(addprefix -i,$(dir $<) $(DTC_INCLUDE)) $(DTC_FLAGS) \
>                 -d $(depfile).dtc.tmp $(dtc-tmp) ; \
>         cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
>
>  quiet_cmd_dtc = DTC     $@
> -      cmd_dtc = $(call __cmd_dtc,dtb)
> +      cmd_dtc = $(call __cmd_dtc,$(DTC),dtb)
>
>  $(obj)/%.dtb: $(src)/%.dts $(DTC) FORCE
>         $(call if_changed_dep,dtc)
> @@ -303,7 +304,7 @@ DT_BINDING_DIR := Documentation/devicetree/bindings
>  DT_TMP_SCHEMA ?= $(objtree)/$(DT_BINDING_DIR)/processed-schema.yaml
>
>  quiet_cmd_dtc_yaml = DTCYAML $@
> -      cmd_dtc_yaml = $(call __cmd_dtc,yaml)
> +      cmd_dtc_yaml = $(call __cmd_dtc,$(DTC_YAML),yaml)
>
>  quiet_cmd_dtb_check =  CHECK   $@
>        cmd_dtb_check =  $(DT_CHECKER) -u $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA) $@
> @@ -313,7 +314,7 @@ define rule_dtc_yaml
>         $(call cmd,dtb_check)
>  endef
>
> -$(obj)/%.dt.yaml: $(src)/%.dts $(DTC) $(DT_TMP_SCHEMA) FORCE
> +$(obj)/%.dt.yaml: $(src)/%.dts $(DTC_YAML) $(DT_TMP_SCHEMA) FORCE
>         $(call if_changed_rule,dtc_yaml)
>
>  dtc-tmp = $(subst $(comma),_,$(dot-target).dts.tmp)
> diff --git a/scripts/dtc/.gitignore b/scripts/dtc/.gitignore
> index b814e6076bdb..e0cf8222c137 100644
> --- a/scripts/dtc/.gitignore
> +++ b/scripts/dtc/.gitignore
> @@ -1,2 +1,3 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  dtc
> +dtc-yaml
> diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
> index ef85f8b7d4a7..c6d7e2b70f08 100644
> --- a/scripts/dtc/Makefile
> +++ b/scripts/dtc/Makefile
> @@ -1,28 +1,22 @@
>  # SPDX-License-Identifier: GPL-2.0
>  # scripts/dtc makefile
>
> -hostprogs                      := dtc
> -always-$(CONFIG_DTC)           += $(hostprogs)
> -always-$(CHECK_DT_BINDING)     += $(hostprogs)
> +# Build the yaml variant for DT schema validation, which requires libyaml
> +# development package. The normal build does not need it.
> +hostprogs                      := dtc dtc-yaml
> +always-$(CONFIG_DTC)           += dtc
> +always-$(CHECK_DTBS)           += dtc-yaml
> +always-$(CHECK_DT_BINDING)     += dtc-yaml
>
> -dtc-objs       := dtc.o flattree.o fstree.o data.o livetree.o treesource.o \
> -                  srcpos.o checks.o util.o
> -dtc-objs       += dtc-lexer.lex.o dtc-parser.tab.o
> +common-objs    := flattree.o fstree.o data.o livetree.o treesource.o \
> +                  srcpos.o checks.o util.o dtc-lexer.lex.o dtc-parser.tab.o
> +dtc-objs       := dtc-no-yaml.o $(common-objs)
> +dtc-yaml-objs  := dtc.o yamltree.o $(common-objs)
> +HOSTLDLIBS_dtc-yaml := -lyaml

Does this work for yocto? As we had this before commit 067c650c456e.
Not clear if this changed for any reason or just 'let's use pkg-config
everywhere'.

Or is there another way to fix yocto issue and we can just check the
header exists. I assume yocto needs some prefix in front of
'/usr/include/yaml.h'?

>  # Source files need to get at the userspace version of libfdt_env.h to compile
>  HOST_EXTRACFLAGS := -I $(srctree)/$(src)/libfdt
>
> -ifeq ($(shell pkg-config --exists yaml-0.1 2>/dev/null && echo yes),)
> -ifneq ($(CHECK_DT_BINDING)$(CHECK_DTBS),)
> -$(error dtc needs libyaml for DT schema validation support. \
> -       Install the necessary libyaml development package.)
> -endif
> -HOST_EXTRACFLAGS += -DNO_YAML
> -else
> -dtc-objs       += yamltree.o
> -HOSTLDLIBS_dtc := $(shell pkg-config yaml-0.1 --libs)
> -endif
> -
>  # Generated files need one more search path to include headers in source tree
>  HOSTCFLAGS_dtc-lexer.lex.o := -I $(srctree)/$(src)
>  HOSTCFLAGS_dtc-parser.tab.o := -I $(srctree)/$(src)
> diff --git a/scripts/dtc/dtc-no-yaml.c b/scripts/dtc/dtc-no-yaml.c
> new file mode 100644
> index 000000000000..f3459e45835f
> --- /dev/null
> +++ b/scripts/dtc/dtc-no-yaml.c
> @@ -0,0 +1,3 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#define NO_YAML
> +#include "dtc.c"
> --
> 2.25.1
>

Re: [PATCH 2/2] scripts/dtc: compile separate dtc-yaml

[Masahiro Yamada]

On Tue, May 5, 2020 at 4:15 AM Rob Herring <robh+dt@kernel.org> wrote:
>
> On Sun, May 3, 2020 at 9:07 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > Marek Behún reported a case where pkg-config fails to detect the
> > libyaml-dev package, which is presumably a bug of the distro.
> >
> > Irrespective of that, I am not a big fan of pkg-config in the Makefile
> > parse stage. The cost of pkg-config is quite small, but it is evaluated
> > everytime we run make, even when we do 'make mrproper'. This commit
> > changes the Makefile to not rely on pkg-config at all.
>
> I don't really love the solution here... I'm inclined to just make
> libyaml always required. Anyone building dtbs should care about
> validating them. However, there's some dts files sprinkled in the tree
> such as DT unittests and I don't want to break allmodconfig for CI,
> 0-day, etc. Though eventually we may have to.
>
> > The normal build should not require libyaml-dev while we need to compile
> > dtc with libyaml for the schema check.
> >
> > Build two dtc variants:
> >
> >   scripts/dtc/dtc      for *.dts -> *.dtb
> >   scripts/dtc/dtc-yaml for *.dts -> *.dt.yaml
>
> My longer term plan is to integrate the schema checks into dtc. This
> would be some sort of plugin to dtc found or specified at run-time. It
> would eliminate the need for 2 passes of dtc and the 2nd case will go
> away.


OK.



> > --- a/scripts/Makefile.lib
> > +++ b/scripts/Makefile.lib
> > @@ -246,6 +246,7 @@ quiet_cmd_gzip = GZIP    $@
> >  # DTC
> >  # ---------------------------------------------------------------------------
> >  DTC ?= $(objtree)/scripts/dtc/dtc
> > +DTC_YAML ?= $(objtree)/scripts/dtc/dtc-yaml
>
> Can we make 'DTC' override both and keep this an internal detail.
>

No. For parallel building *.dtb and *.dt.yaml,
they must be separate instances.


> > +HOSTLDLIBS_dtc-yaml := -lyaml
>
> Does this work for yocto? As we had this before commit 067c650c456e.
> Not clear if this changed for any reason or just 'let's use pkg-config
> everywhere'.
>
> Or is there another way to fix yocto issue and we can just check the
> header exists. I assume yocto needs some prefix in front of
> '/usr/include/yaml.h'?
>

My bad - I missed 067c650c456e

We need pkg-config to deal with yocto.


Sorry, I take back this series.

-- 
Best Regards
Masahiro Yamada

Re: [PATCH 2/2] scripts/dtc: compile separate dtc-yaml

[Masahiro Yamada]

On Tue, May 5, 2020 at 12:04 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Tue, May 5, 2020 at 4:15 AM Rob Herring <robh+dt@kernel.org> wrote:
> >
> > On Sun, May 3, 2020 at 9:07 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> > >
> > > Marek Behún reported a case where pkg-config fails to detect the
> > > libyaml-dev package, which is presumably a bug of the distro.
> > >
> > > Irrespective of that, I am not a big fan of pkg-config in the Makefile
> > > parse stage. The cost of pkg-config is quite small, but it is evaluated
> > > everytime we run make, even when we do 'make mrproper'. This commit
> > > changes the Makefile to not rely on pkg-config at all.
> >
> > I don't really love the solution here... I'm inclined to just make
> > libyaml always required. Anyone building dtbs should care about
> > validating them. However, there's some dts files sprinkled in the tree
> > such as DT unittests and I don't want to break allmodconfig for CI,
> > 0-day, etc. Though eventually we may have to.
> >
> > > The normal build should not require libyaml-dev while we need to compile
> > > dtc with libyaml for the schema check.
> > >
> > > Build two dtc variants:
> > >
> > >   scripts/dtc/dtc      for *.dts -> *.dtb
> > >   scripts/dtc/dtc-yaml for *.dts -> *.dt.yaml
> >
> > My longer term plan is to integrate the schema checks into dtc. This
> > would be some sort of plugin to dtc found or specified at run-time. It
> > would eliminate the need for 2 passes of dtc and the 2nd case will go
> > away.
>
>
> OK.
>
>
>
> > > --- a/scripts/Makefile.lib
> > > +++ b/scripts/Makefile.lib
> > > @@ -246,6 +246,7 @@ quiet_cmd_gzip = GZIP    $@
> > >  # DTC
> > >  # ---------------------------------------------------------------------------
> > >  DTC ?= $(objtree)/scripts/dtc/dtc
> > > +DTC_YAML ?= $(objtree)/scripts/dtc/dtc-yaml
> >
> > Can we make 'DTC' override both and keep this an internal detail.
> >
>
> No. For parallel building *.dtb and *.dt.yaml,
> they must be separate instances.
>
>
> > > +HOSTLDLIBS_dtc-yaml := -lyaml
> >
> > Does this work for yocto? As we had this before commit 067c650c456e.
> > Not clear if this changed for any reason or just 'let's use pkg-config
> > everywhere'.
> >
> > Or is there another way to fix yocto issue and we can just check the
> > header exists. I assume yocto needs some prefix in front of
> > '/usr/include/yaml.h'?
> >
>
> My bad - I missed 067c650c456e
>
> We need pkg-config to deal with yocto.
>
>
> Sorry, I take back this series.


On my second thought, we can search libyaml
in non-standard path without pkg-config.


Kbuild provides a way to specify additional flags
for building host tools.

make  HOSTCFLAGS=<install-dir-in-yocto>/include
      HOSTLDFLAGS=<install-dir-in-yocto>/lib




-- 
Best Regards
Masahiro Yamada