Re: Behaviour of kernel makefiles when entering a subdir using a config symbol = m

[Michal Marek <mmarek@suse.com>]

Dne 10.12.2015 v 21:46 Sam Ravnborg napsal(a):
> On Thu, Dec 10, 2015 at 09:44:45AM +0200, Tomi Valkeinen wrote:
>> We have three drivers (one fbdev, two drm), each of which can be built
>> as a module. But each of them also may require small boot-time setup,
>> which needs to be built-in.
>>
>> I can get around the problem by entering the dir with obj-y, or by
>> creating a new extra config define which is y/n, and using that in the
>> makefile. The former makes make enter the dir even if the driver is not
>> enabled, and latter creates a config symbol only to solve this problem.
> The extra config symbol is the most elegant solution here IMO.
> Make sure to document that this config symbol enables the boot-time
> setup stuff.

Agreed. We could tech kbuild to look for built-in.o also in obj-m
subdirs, but I'm quite sure it would break a Makefile or two. We had
this case when adding support for modname-m recently, a couple of
Makefiles did not expect this and broke.

Michal