Re: [Buildroot] [PATCH] configs/kontron_bl_imx8mm_defconfig: fix build failure with u-boot 2022.04

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Heiko,

On Tue, 9 Aug 2022 10:06:02 +0200
Thomas Petazzoni via buildroot <buildroot@buildroot.org> wrote:

> But this is not normal, because:
> 
> UBOOT_MAKE_OPTS += \
>         CROSS_COMPILE="$(TARGET_CROSS)" \
>         ARCH=$(UBOOT_ARCH) \
>         HOSTCC="$(HOSTCC) $(subst -I/,-isystem /,$(subst -I /,-isystem /,$(HOST_CFLAGS)))" \
>         HOSTLDFLAGS="$(HOST_LDFLAGS)" \
>         $(call qstrip,$(BR2_TARGET_UBOOT_CUSTOM_MAKEOPTS))
> 
> see we're passing HOSTLDFLAGS here? It contains -L$(HOST_DIR)/lib. So
> it means there is also something wrong in U-Boot in that it doesn't use
> $(HOSTLDFLAGS).

Could you try this change in U-Boot:

diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index 69983a19a44..7624304e3e9 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -89,7 +89,7 @@ hostcxx_flags  = -Wp,-MD,$(depfile) $(__hostcxx_flags)
 # Create executable from a single .c file
 # host-csingle -> Executable
 quiet_cmd_host-csingle         = HOSTCC  $@
-      cmd_host-csingle = $(HOSTCC) $(hostc_flags) -o $@ $< \
+      cmd_host-csingle = $(HOSTCC) $(hostc_flags) $(KBUILD_HOSTLDFLAGS) -o $@ $< \
                $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(@F))
 $(host-csingle): $(obj)/%: $(src)/%.c FORCE
        $(call if_changed_dep,host-csingle)

(without your pkg-config patch, of course).

Indeed, scripts/Makefile.host is a copy of the kernel's
scripts/Makefile.host, and the kernel copy does use KBUILD_HOSTLDFLAGS
when building host tools that are based on a single source file, but
for some reason the U-Boot copy does not have it, which doesn't make
much sense.

I think it doesn't mean your pkg-config patch is bogus: it still makes
sense to use pkg-config when possible, but I also think not passing
KBUILD_HOSTLDFLAGS is incorrect.

Of course, if it works, I think both patches should be submitted to
U-Boot upstream.

Could you have a look?

Thanks a lot!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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