[Buildroot] Cannot build Custom Kernel Module

[Stephen Beckwith]

On Wed, Apr 13, 2016 at 11:37 AM, Arnout Vandecappelle <arnout at mind.be>
wrote:

>  Hi Stephen,
>
>  Please don't top-post, but reply in-line like I do below. I realize that
> gmail doesn't make that easy :-)
>
> Yea, sorry - thought of that after clicking send. . . .  :(


> On 04/13/16 16:38, Stephen Beckwith wrote:
>
>> Arnout,
>>     THANK YOU very much!  The problem wasn't so much an issue with the
>> $eval,
>> which for the life of me I don't remember where I copied that from but it
>> was
>> the "missing from external.mk" that solved it!!  Thanks for
>> the pointer! (sometimes we forget these little steps. . .)
>> So external.mk now has:
>> # Does the Kernel Modules first:
>> include $(sort $(wildcard $(BR2_EXTERNAL)/netapp/kmod*/*.mk))
>> and the directory is now:  kmod_gpio - along with the associated "ripple
>> effect" -
>> The good news is:  Does the Rsync and starts off the build.
>> I've reduced the kmod_gpio.mk to:
>> KMOD_GPIO_VERSION = 0.1.0
>> KMOD_GPIO_LICENSE = Public Domain
>> KMOD_GPIO_SITE = $(BR2_EXTERNAL)/netapp/kmod_gpio
>> KMOD_GPIO_SITE_METHOD = local
>>
>
>  As you have noticed, BR2_EXTERNAL is not exported so you can't refer to
> it from the package Makefile. The proper way is to add here:
>
> KMOD_GPIO_MODULE_MAKE_OPTS = NETAPP_DIR=$(BR2_EXTERNAL)

==> Interesting. . .  This DOES work! ! ! THANKS!!

>


>
>
>> $(eval $(kernel-module))
>> $(eval $(generic-package))
>>
>> And I have a Makefile in the directory that is:
>>
>> #inform the kernel that a module needs to be build
>> obj-m :=gpio_module.o
>>
>> # Global Includes here
>> GBL_INCLUDES = $(BR2_EXTERNAL)/netapp/include
>> KNL_INCLUDES = $(BR2_EXTERNAL)/netapp/include/kernel
>>
>
>  And here you use GBL_INCLUDES=$(NETAPP_DIR)/include
>
==> and again, this worked, at least I don't get the include errors now. .
.
Now, fixing all the errors due to porting from a 2.6.32 kernel to 4.1.4
kernel :(

Another quick question, if I may:
 -  The build root version I have is 2015.08.01 - this supports a 4.1.4
kernel.  Since 4.1.x is an LTS kernel, is there a way to tell/configure
Buildroot to fetch a patch for the latest . release (currently 4.1.21)???
Meaning, a patch from 4.1.4 -> 4.1.21?   I've done something like this in
the past, wasn't easy.

Thanks again!!!
Be safe there in Belgium. . .

Regards,
Stephen

>
>
>  Regards,
>  Arnout
>
>
>> #Add here the CFLAGS to pass in to get the Defined Symbol
>> CFLAGS_gpio_module.o := -DCONFIG_NETAPP_HWDD -I$(GBL_INCLUDES)
>> -I$(KNL_INCLUDES)
>>
>> {fixed the bad,bad CFLAGS issue :) }
>>
>> However, I get a failure to build, due to missing headers, which are
>> located in
>> the GBL_INCLUDES path.  It seems for kernel modules, the $(BR2_EXTERNAL)
>> is not
>> being honored, as shown below.  Does this get passed through?  Is it OK to
>> "reach back" to the source directory for the includes?
>>
> [snip]
>
> --
> Arnout Vandecappelle      arnout dot vandecappelle at essensium dot com
> Senior Embedded Software Architect . . . . . . +32-478-010353 (mobile)
> Essensium, Mind division . . . . . . . . . . . . . . http://www.mind.be
> G.Geenslaan 9, 3001 Leuven, Belgium . . . . . BE 872 984 063 RPR Leuven
>
> LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
> GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF
>
>
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