Cross compile rules update

[Loïc Minier]

On Mon, Oct 11, 2010, Jan, Sebastien wrote:
> I was able to cross-compile with the following hack:
> diff --git a/debian/rules.d/0-common-vars.mk b/debian/rules.d/0-common-vars.mk
> index 66d3900..b4d7a8a 100644
> --- a/debian/rules.d/0-common-vars.mk
> +++ b/debian/rules.d/0-common-vars.mk
> @@ -106,9 +106,13 @@ endif
>  # an x86'en schroot. This is the only way to build all of the packages
>  # (except for tools).
>  #
> +ifneq ($(CROSS_COMPILE),)
> +       CROSS_COMPILE := CROSS_COMPILE=$(CROSS_COMPILE)
> +else
>  ifneq ($(DEB_BUILD_GNU_TYPE),$(DEB_HOST_GNU_TYPE))
>         CROSS_COMPILE ?= CROSS_COMPILE=$(DEB_HOST_GNU_TYPE)-
>  endif
> +endif

 Oh right, the issue is probably that you pass the right CROSS_COMPILE
 with the value "some-cross-prefix-" that the downstream kernel build
 expects, but the kernel debian/rules machinery expects this variable to
 contain "CROSS_COMPILE=some-cross-prefix-", and not just
 "some-cross-prefix-".

 A nicer fix would be to rename the CROSS_COMPILE=foo argument to the
 kernel build differently, or to only store its value in the variable.

 That is, either:
    ifneq ($(DEB_BUILD_GNU_TYPE),$(DEB_HOST_GNU_TYPE))
    CROSS_COMPILE_ARG ?= CROSS_COMPILE=$(DEB_HOST_GNU_TYPE)-
    endif
    [...]
    $(MAKE) $(CROSS_COMPILE_ARG)

 or, nicer:
    ifneq ($(DEB_BUILD_GNU_TYPE),$(DEB_HOST_GNU_TYPE))
    CROSS_COMPILE ?= $(DEB_HOST_GNU_TYPE)-
    endif
    [...]
    $(MAKE) CROSS_COMPILE=$(CROSS_COMPILE)

 the latter will result in make being called with "CROSS_COMPILE=" in
 native builds, which should be just fine, but if you really want to
 avoid it you could use a $(if ) construct on the make invocation.

    Cheers,
-- 
Loïc Minier