[PATCH] iw: Makefile: support out-of-tree builds

[PATCH] iw: Makefile: support out-of-tree builds

[Maxin John]

Enable out-of-tree builds without modifying the source tree.
Out-of-tree builds are required by build frameworks such as OpenEmbedded.

Signed-off-by: Maxin John <maxin.john@gmail.com>
---
 Makefile | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/Makefile b/Makefile
index 2652fac4e6ee..fbbc3042cd37 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,8 @@
 MAKEFLAGS += --no-print-directory
 
+SRCDIR := $(dir $(lastword $(MAKEFILE_LIST)))
+VPATH := $(SRCDIR)
+
 PREFIX ?= /usr
 SBINDIR ?= $(PREFIX)/sbin
 MANDIR ?= $(PREFIX)/share/man
@@ -21,7 +24,11 @@ CFLAGS += -D__SANE_USERSPACE_TYPES__
 CFLAGS += $(CFLAGS_EVAL)
 CFLAGS += $(EXTRA_CFLAGS)
 
-_OBJS := $(sort $(patsubst %.c,%.o,$(wildcard *.c)))
+CPPFLAGS += -I$(SRCDIR)
+CPPFLAGS += -I.
+
+_SRCS := $(wildcard $(SRCDIR)/*.c)
+_OBJS := $(sort $(patsubst $(SRCDIR)/%.c,%.o,$(_SRCS)))
 VERSION_OBJS := $(filter-out version.o, $(_OBJS))
 OBJS := $(VERSION_OBJS) version.o
 
@@ -92,16 +99,18 @@ endif
 
 all: $(ALL)
 
-version.c: version.sh $(patsubst %.o,%.c,$(VERSION_OBJS)) nl80211.h iw.h Makefile \
-		$(wildcard .git/index .git/refs/tags)
+version.c: $(SRCDIR)/version.sh \
+	$(patsubst %.o,$(SRCDIR)/%.c,$(VERSION_OBJS)) \
+	$(SRCDIR)/nl80211.h $(SRCDIR)/iw.h $(SRCDIR)/Makefile \
+	$(wildcard $(SRCDIR)/.git/index $(SRCDIR)/.git/refs/tags)
 	@$(NQ) ' GEN ' $@
-	$(Q)./version.sh $@
+	$(Q)$(SRCDIR)/version.sh $@
 
-nl80211-commands.inc: nl80211.h
+nl80211-commands.inc: $(SRCDIR)/nl80211.h
 	@$(NQ) ' GEN ' $@
-	$(Q)sed 's%^\tNL80211_CMD_%%;t n;d;:n s%^\([^=]*\),.*%\t[NL80211_CMD_\1] = \"\L\1\",%;t;d' nl80211.h | grep -v "reserved" > $@
+	$(Q)sed 's%^\tNL80211_CMD_%%;t n;d;:n s%^\([^=]*\),.*%\t[NL80211_CMD_\1] = \"\L\1\",%;t;d' $(SRCDIR)/nl80211.h | grep -v "reserved" > $@
 
-%.o: %.c iw.h nl80211.h nl80211-commands.inc
+%.o: %.c $(SRCDIR)/iw.h $(SRCDIR)/nl80211.h nl80211-commands.inc
 	@$(NQ) ' CC  ' $@
 	$(Q)$(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<
 
-- 
2.47.3

Re: [PATCH] iw: Makefile: support out-of-tree builds

[Johannes Berg]

On Thu, 2026-04-23 at 14:31 +0300, Maxin John wrote:
> Enable out-of-tree builds without modifying the source tree.
> Out-of-tree builds are required by build frameworks such as OpenEmbedded.

You should probably say how this is intended to be used, clearly not in
the O= way that the kernel has, for example.
 
> +SRCDIR := $(dir $(lastword $(MAKEFILE_LIST)))

That doesn't work if there's whitespace anywhere along the path.

> +CPPFLAGS += -I$(SRCDIR)
> +CPPFLAGS += -I.

The "-I." seems questionable since you evidently intend to have "."
*not* be the source dir?


Overall it might be simpler to actually do it with the kernel-style O=
so you just need to change all the outputs, rather than all the inputs?

johannes

Re: [PATCH] iw: Makefile: support out-of-tree builds

[Maxin John]

Hi Johannes,

Thanks for the review comments.

On Mon, Apr 27, 2026 at 11:43:54AM +0200, Johannes Berg wrote:
> On Thu, 2026-04-23 at 14:31 +0300, Maxin John wrote:
> > Enable out-of-tree builds without modifying the source tree.
> > Out-of-tree builds are required by build frameworks such as OpenEmbedded.
> 
> You should probably say how this is intended to be used, clearly not in
> the O= way that the kernel has, for example.

I will clarify the intended usage in the next iteration.  

> > +SRCDIR := $(dir $(lastword $(MAKEFILE_LIST)))
> 
> That doesn't work if there's whitespace anywhere along the path.
> 
> > +CPPFLAGS += -I$(SRCDIR)
> > +CPPFLAGS += -I.
> 
> The "-I." seems questionable since you evidently intend to have "."
> *not* be the source dir?

The -I. was intended to ensure that generated files such as
nl80211-commands.inc, which are produced in the build directory,
 remain discoverable by the compiler. Agree that it doesn't look right
and I will update it. 

> 
> Overall it might be simpler to actually do it with the kernel-style O=
> so you just need to change all the outputs, rather than all the inputs?

Got it. I will update it as per your comments and send a v2.

> 
> johannes

Best Regards,
Maxin

Re: [PATCH] iw: Makefile: support out-of-tree builds

[Johannes Berg]

On Tue, 2026-04-28 at 20:12 +0300, Maxin John wrote:
> 
> > > +CPPFLAGS += -I.
> > 
> > The "-I." seems questionable since you evidently intend to have "."
> > *not* be the source dir?
> 
> The -I. was intended to ensure that generated files such as
> nl80211-commands.inc, which are produced in the build directory,
>  remain discoverable by the compiler. Agree that it doesn't look right
> and I will update it. 

Oh, I guess that makes sense, maybe just add a comment? But that's after
guessing you somehow intend to call 'make -f ../src/Makefile' or
something, which seems a little odd to me?

johannes