[Buildroot] Multi-File Kernel Module Build Fails

[Stephen Beckwith]

Hi Thomas,
   The MAKE_OPTS and 2 variables are necessary, as the include directory
does NOT get copied into the output/build directory.  I see what you did,
using $(src) - but that's not where the includes are.
   I have ~ 40 modules/drivers/apps that reference these includes, they are
common across these various software components.
   Your suggestion failed, due to the includes not being:
-DCONFIG_NETAPP_HWDD -I/home/sbeckwith/HBE-1/hwdd/
*output/build/kmod_mem-0.1.0*/./include
-I/home/sbeckwith/HBE-1/hwdd/output/build/kmod_mem-0.1.0/./include/kernel

Again, IF I have a single source file module, the setup I have works
perfectly, the include directory outside of the output/build tree gets
referenced and the build is OK.  Only when I have more than one source file
involved does build root not seem to pass the MAKE_OPTS through.

Question:
  -  is it allowed in buildroot to access common include header files
outside of the build directory?  Or should these be somehow copied (via
rsync) as a separate config like item?

Regards,
Stephen

On Tue, Apr 26, 2016 at 4:25 PM, Thomas Petazzoni <
thomas.petazzoni at free-electrons.com> wrote:

> Hello,
>
> (Resending with the Buildroot mailing list in Cc. Please always keep
> the list in Cc. Thanks!)
>
> On Tue, 26 Apr 2016 16:20:17 -0400, Stephen Beckwith wrote:
>
> > KMOD_MEM_MODULE_MAKE_OPTS = NETAPP_DIR=$(BR2_EXTERNAL)/netapp
>
> Get rid of this.
>
> > #inform the kernel that a module needs to be build
> > obj-m := hwdd_memory.o
> > hwdd_memory-objs := hwdd_mem.o hwdd_memalgo.o hwdd_cache_algos.o
> >
> > # Global Includes here
> > GBL_INCLUDES = $(NETAPP_DIR)/include
> > KNL_INCLUDES = $(NETAPP_DIR)/include/kernel
>
> And those two variable definitions.
>
> > #Add here the CFLAGS to pass in to get the Defined Symbol
> > CFLAGS_hwdd_memory.o := -DCONFIG_NETAPP_HWDD -I$(GBL_INCLUDES)
> > -I$(KNL_INCLUDES)
>
> And replace this by:
>
> ccflags-y := -DCONFIG_NETAPP_HWDD -I$(src)/include -I$(src)/include/kernel
>
> Again, I've spent time creating an example that I've tested. Since I
> can't reproduce your test case, please try my example, which you can
> test as I'm providing the entire source code :)
>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com
>
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