[Buildroot] [PATCH v4] linux-headers: allow use of headers from kernel "package" selected

[Yann E. MORIN <yann.morin.1998@free.fr>]

Peter, Thomas, All,

On 2016-01-19 11:37 +0100, Peter Korsgaard spake thusly:
> >>>>> "Thomas" == Thomas Petazzoni <thomas.petazzoni@free-electrons.com> writes:
>  > Dear Peter Korsgaard,
>  > On Tue, 19 Jan 2016 11:29:08 +0100, Peter Korsgaard wrote:
> 
>  >> Well, linux-headers doesn't need to do much - So with a bit of care I
>  >> think you can.
>  >> 
>  >> E.G. something like (completely untested):
>  >> 
>  >> ifeq ($(LINUX_HEADERS_FROM_KERNEL),y)
>  >> # no source
>  >> LINUX_HEADERS_SOURCE =
>  >> LINUX_HEADERS_DEPENDENCIES += linux-configure
> 
>  > The configure step of a package depends on the dependencies of that
>  > package. So linux-configure depends on toolchain. And toolchain depends
>  > on linux-headers -> recursive dependency.
> 
>  > Another try ? :-)
> 
> Then linux-patch, we afaik don't need a configured linux kernel to make headers_install

Indeed, that's a good idea. We propbably could use set:

    LINUX_HEADERS_PATCH_DEPENDENCIES = linux

which will guarantee that linux is patched before linux-headers is
configured (in the Buildroot sense).

Then, we basically could do:

    define LINUX_HEADERS_INSTALL_STAGING_CMDS
        $(MAKE) -C $(LINUX_DIR) INSTALL_HDR_PATH=$(STAGING_DIR)/usr
    endef

(with extra variables as done today, of course...)

There, we can use $(LINUX_DIR) because the macro is only expanded in a
make rule, so we should be fine. Hopefully...

I can have a look at this.

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'