[yocto] module do_configure depends on kernel .config and headers

[Vajzovic, Tom]

Hi Bruce,

From: Bruce Ashfield
Sent: 15 April 2016 18:15
> On Fri, Apr 15, 2016 at 12:02 PM, Vajzovic, Tom wrote:
>>
>> I am using a meta layer provided by a SOM manufacturer.
>> They have a recipe which sets:
>
> What branch are you using ?

Fido.
 
>> inherit module
>>
>> export KLIB_BUILD="${STAGING_KERNEL_DIR}"
>> export KLIB="${D}"
>> 
>> and then its do_configure script calls make, and the Makefile
>> expects $(KLIB_BUILD)/.config to exist, and the kernel headers to be
>> in the same place.
>>
>> This sometimes succeeds and sometimes fails, which I presume is to
>> do with the order that the other entries in the run-queue are
>> executed.
>> 
>> I thought that this might be because the dependency on the kernel
>> .config and headers is not correctly recorded in the recipe.
>> 
>> I added a .bbappend file to the recipe in my own layer which
>> contains:
>>
>> do_configure[depends] += "virtual/kernel:do_shared_workdir"
>>
>> But this has not resolved the problem.  I have used
>> bitbake-layers to verify that my bbappend is being applied.
>>
>> So my questions are:
>>
>> Is $(KLIB_BUILD) the correct place to look for the kernel
>> .config and headers?
>
> The .config is in: STAGING_KERNEL_BUILDDIR, that also has any
> generated files as part of the build.
>
> The headers are in the shared_workdir, as you had found:
> STAGING_KERNEL_DIR

I have a copy of .config in both STAGING_KERNEL_DIR and 
STAGING_KERNEL_BUILDDIR.  They differ only on that the latter has
CONFIG_LOCALVERSION added.  Is this normal?  Can I depend on the
copy in STAGING_KERNEL_DIR? I think that is what the configure
script is currently using.  How else might it differ?

>> What is the correct way to record the dependency in the recipe?
>>
>> Why isn't this done in module.bbclass?  Wouldn't all modules depend
>> on the kernel headers?
>
> It pretty much does, with this in module-base.bbclass:
> do_configure[depends] += "virtual/kernel:do_compile_kernelmodules"

In my Fido modules-base.bbclass I have exactly:

do_configure[depends] += "virtual/kernel:do_shared_workdir"

So this means that my bbappend is a no-op (I only looked as far as
modules.bbclass; I missed modules-base).

Thanks,
Tom