[Buildroot] [PATCH 01/11 v2] package-infra: add helper to build kernel modules

[Arnout Vandecappelle <arnout@mind.be>]

On 06/12/15 19:46, Yann E. MORIN wrote:
> Arnout, All,
> 
> On 2015-06-12 00:44 +0200, Arnout Vandecappelle spake thusly:
>> On 06/10/15 21:22, Yann E. MORIN wrote:
>>> The Linux kernel offers a nice and easy-to-use infra to build
>>> out-of-tree kernel modules.
> [--SNIP--]
>>> diff --git a/package/pkg-kernel-module.mk b/package/pkg-kernel-module.mk
>>> new file mode 100644
>>> index 0000000..608c9e6
>>> --- /dev/null
>>> +++ b/package/pkg-kernel-module.mk
>>> @@ -0,0 +1,89 @@
>>> +################################################################################
>>> +# kernel module infrastructure for building Linux kernel modules
>>> +#
>>> +# This file implements an infrastructure that eases development of package
>>> +# .mk files for out-of-tree Linux kernel modules. It should be used for all
>>> +# packages that build a Linux kernel module using the kernel's out-of-tree
>>> +# buildsystem, unless they use a complex custom build-system.
>>
>>  buildsystem, build-system. What about consistently choosing "build system"? :-)
> 
> I think we've settled for "buildsystem" in other places, so I'll stick
> to that (and fix here).

 OK. I was joking about the "build system".

> 
>>> +# In terms of implementation, this infrastructure relies on another package
>>> +# infrastructure, and only defines post-build and post-install hooks, so that
>>> +# packages can both build user-space (with any of the other *-package infra)
>>> +# and/or build kernel modules.
>>
>> # The kernel-module infrastructure requires the packages that use it to also
>> # include another package infrastructure. kernel-module only defines post-build
> 
> s/include/use/ because we're not 'including' pkg infras, we're not even
> calling them, we're evaluating them. So I'd still word that as 'use' if
> you don't mind. ;-)

 Yep that's better.

> 
>> # and post-install hooks. This allows the package to build both kernel modules
>> # and/or user-space components (with any of the other *-package infra).
> 
> Otherwise, OK, it's simpler and more explixit thn what I wrote.
> 
>>> +#
>>> +# As such, it is to be used in conjunction with another *-package infra,
>>> +# like so:
>>> +#
>>> +#   $(eval $(kernel-module))
>>> +#   $(eval $(generic-package))
>>> +#
>>> +# Note: if the caller needs access to the kernel modules (either after they
>>> +# are built or after they are installed), it will have to define its own
>>> +# post-build/install hooks after calling kernel-module, but before calling
>>
>>  after -> *after*
> 
> OK. I guess ditto for: before -> *before* , no?

 Yeah you're right.

> 
>>> +# the other *-package infra, like so:
>>> +#
>>> +#   $(eval $(kernel-module))
>>> +#   define FOO_MOD_TWEAK
>>> +#   	# do something
>>> +#   endef
>>> +#   FOO_POST_BUILD_HOOKS += FOO_MOD_TWEAK
>>> +#   $(eval $(generic-package))
>>> +#
>>> +# Note: this infra does not check that the kernel is enabled; it is expected
>>> +# to be enforced at the Kconfig level with proper 'depends on'.
>>> +################################################################################
>>> +
>>> +################################################################################
>>> +# inner-kernel-module -- generates the make targets needed to support building
>>> +# a kernel module
>>> +#
>>> +#  argument 1 is the lowercase package name
>>
>>  Is there any reason to keep this, since it's not used?
> 
> Well, I wanted to keep it as much aligned to existing infras as
> possible, even though we're not using it.

 Yeah, but you did remove the rest of the usual arguments... Anyway, I'm OK with
keeping the first argument if you want.


 Regards,
 Arnout

> 
>>> +#  argument 2 is the uppercase package name
>>> +################################################################################
>>> +
>>> +define inner-kernel-module
>>> +
>>> +# The kernel must be built first.
>>> +$(2)_DEPENDENCIES += linux
>>> +
>>> +# This is only defined in some infrastructures (e.g. autotools, cmake), but
>>> +# not in others (generic). So define it if not already defined.
>>                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>                               So define it here as well.
> 
> OK.
> 
> Thanks! :-)
> 
> Regards,
> Yann E. MORIN.
> 


-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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