Re: [PATCH RESEND net-next] tools: ynl: Fix out-of-tree build for ynltool

[Nicolai Buchwitz <nb@tipi-net.de>]

Hi Maxime

On 10.9.2026 18:54, Maxime Chevallier (Netdev Foundation) wrote:
> After the blamed commit, running a out-of-tree build for ynltool fails 
> :
> 
>   # make -C tools/net/ynl/ynltool O=/tmp/o1
>   make: Entering directory 'tools/net/ynl/ynltool'
>   make: *** No rule to make target '/tmp/o1/json_writer.o', needed by 
> '/tmp/o1/ynltool'.  Stop.
> 
> ynltool's Makefile correctly accounts for $(OUTPUT) to get the list of
> object files to generate :
> 
> OBJS := $(patsubst %.c,$(OUTPUT)%.o,$(SRCS))
> 
> but it never actually set $(OUTPUT) before the blamed commit, meaning
> that out-of-tree buils of ynltool were always actually in-tree.
> 
> Now, the O= parameter is correctly accounted for, and the %o: %c rule 
> fails.
> 
> Let's update the %o: %c rule to also use $(OUTPUT).
> 
> Reported-by: Bobby Eshleman <bobbyeshleman@gmail.com>
> Closes: 
> https://lore.kernel.org/all/aqCyWQxqKDuQnZYR@devvm29614.prn0.facebook.com/
> Fixes: 917f713b4ec4 ("tools: ynl: Allow cross-compiling ynl and 
> associated tools")
> Signed-off-by: Maxime Chevallier (Netdev Foundation) 
> <maxime.chevallier@bootlin.com>
> ---
> Re-sending, the previous submission didn't reach netdev@ :/
> Fixes a bug in net-next, so targetting net-next.
> 
>  tools/net/ynl/ynltool/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/net/ynl/ynltool/Makefile 
> b/tools/net/ynl/ynltool/Makefile
> index b8c67cdb4fdf..1053e7606c86 100644
> --- a/tools/net/ynl/ynltool/Makefile
> +++ b/tools/net/ynl/ynltool/Makefile
> @@ -31,7 +31,7 @@ $(YNLTOOL): ../libynl.a $(OBJS)
>  	$(Q)echo -e "\tLINK $@"
>  	$(Q)$(CC) $(CFLAGS) -o $@ $(OBJS) ../libynl.a -lm
> 
> -%.o: %.c ../libynl.a
> +$(OUTPUT)%.o: %.c ../libynl.a

There is a second issue if I'm not mistaken:

   out=$(mktemp -d)
   make -C tools/net/ynl/ynltool O="$out"
   touch tools/net/ynl/ynltool/main.h
   make -C tools/net/ynl/ynltool O="$out"

-> make: Nothing to be done for 'all'.

Add $(OUTPUT) to the wildcard include

   include $(wildcard $(OUTPUT)*.d)

and it works.

>  	$(Q)echo -e "\tCC $@"
>  	$(Q)$(COMPILE.c) -MMD -c -o $@ $<

Thanks,
Nicolai