From: Michal Marek <mmarek@suse.cz>
To: Mark Brown <broonie@kernel.org>
Cc: linaro-kernel@lists.linaro.org, linux-kbuild@vger.kernel.org,
John Rigby <john.rigby@linaro.org>,
Mark Brown <broonie@linaro.org>
Subject: Re: [PATCH] kbuild: Allow scripts/* to be cross compiled
Date: Fri, 09 Aug 2013 14:36:27 +0200 [thread overview]
Message-ID: <5204E24B.3090608@suse.cz> (raw)
In-Reply-To: <1376046432-12588-1-git-send-email-broonie@kernel.org>
On 9.8.2013 13:07, Mark Brown wrote:
> From: John Rigby <john.rigby@linaro.org>
>
> Cross compiling the binaries in scripts/* is not possible
> because various makefiles assume that $(obj)/whatever is
> executable on the build host.
What is the use case for cross-compiling them? If you have a powerful
enough target machine to build the kernel on it, you can as well compile
the host scripts natively, can't you? But maybe I'm missing something, I
do not cross-compile the kernel on a daily basis. Are there other
projects that have such feature in their build system?
> This patch introduces a new variable called KBUILD_SCRIPTROOT
> that points to script/binaries to use while cross compiling.
>
> Usage:
>
> Build scripts for the build host:
> make O=path/to/buildhost/buildscripts \
> silentoldconfig prepare scripts
> Then cross build script for target:
> make O=path/to/target/buildscripts \
> HOSTCC=$CROSS_COMPILE \
> KBUILD_SCRIPTROOT=path/to/buildhost/buildscripts
> silentoldconfig prepare scripts
Note that a build that uses KBUILD_SCRIPTROOT cannot detect if the
scripts are up to date and cannot rebuild them. This must be documented.
> This patch does not use KBUILD_SCRIPTROOT for all script invocations
> it only redefines the following if KBUILD_SCRIPTROOT is defined.
>
> scripts/Makefile.build
> scripts/basic/fixdep --> $(KBUILD_SCRIPTROOT)/scripts/basic/fixdep
>
> scripts/kconfig/Makefile
> $(obj)/conf --> $(KBUILD_SCRIPTROOT)/scripts/kconfig/conf
>
> scripts/mod/Makefile
> $(obj)mk_elfconfig --> $(KBUILD_SCRIPTROOT)/scripts/mod/mk_elfconfig
OK, but you might need to add a couple of more of them, like
lib/gen_crc32table.
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index 547e15d..09aa90c 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -222,11 +222,15 @@ if_changed = $(if $(strip $(any-prereq) $(arg-check)), \
> $(echo-cmd) $(cmd_$(1)); \
> echo 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd)
>
> +ifeq ($(KBUILD_SCRIPTROOT),)
> +KBUILD_SCRIPTROOT=.
> +endif
> +
This should be set in the top level Makefile once.
Thanks,
Michal
prev parent reply other threads:[~2013-08-09 12:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-09 11:07 [PATCH] kbuild: Allow scripts/* to be cross compiled Mark Brown
2013-08-09 12:32 ` Sam Ravnborg
2013-08-09 15:00 ` Mark Brown
2013-08-09 15:13 ` Sam Ravnborg
2013-08-09 15:27 ` Mark Brown
2013-08-09 15:35 ` Michal Marek
2013-08-09 16:08 ` Mark Brown
2013-08-09 12:36 ` Michal Marek [this message]
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