linux-kernel - Re: [PATCH] Fix CONFIG_CROSS

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Date:	Wed, 23 Jun 2010 00:44:39 -0300
From:	Tiago Maluta <tiago.maluta@...il.com>
To:	Michal Marek <mmarek@...e.cz>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Roland McGrath <roland@...hat.com>,
	linux-kbuild@...r.kernel.org
Subject: Re: [PATCH] Fix CONFIG_CROSS_COMPILE issue in .config

On Mon, Jun 21, 2010 at 4:54 PM, Michal Marek <mmarek@...e.cz> wrote:
> On 21.6.2010 21:06, Andrew Morton wrote:
>> On Thu, 17 Jun 2010 12:50:52 +0000
>> Tiago Maluta <tiago.maluta@...il.com> wrote:
>>
>>> Linux has an recent option to define CROSS_COMPILE in menuconfig.
>>>
>>> Typically, one of the options when building for another target is
>>> ('arm' is just an example):
>>>
>>> # make ARCH=arm CROSS_COMPILE=arm-cc O=../build
>>>
>>> If I omit CROSS_COMPILE and use the new way in .config:
>>> CONFIG_CROSS_COMPILE="arm-cc"
>>>
>>> I got:
>>>
>>>    cc1: error: unrecognized command line option "-mlittle-endian"
>>>    cc1: error: unrecognized command line option "-mabi=aapcs-linux"
>>>    cc1: error: unrecognized command line option "-mno-thumb-interwork"
>>>    /usr/src/linux/kernel/bounds.c:1: error: bad value (armv5t) for
>>> -march= switch
>>>    /usr/src/linux/kernel/bounds.c:1: error: bad value (armv5t) for
>>> -mtune= switch
>>>    make[2]: *** [kernel/bounds.s] Error 1
>>>    make[1]: *** [prepare0] Error 2
>>>    make: *** [sub-make] Error 2
>>>
>>> Verbose output clearly says that I'm using the host compiler instead
>>> cross compiler.
>>> This patch fixed my problem:
>>>
>>> ---
>>> __Makefile |______ 2 +-
>>> __1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/Makefile b/Makefile
>>> index d49d96c..5a6c7d5 100644
>>> --- a/Makefile
>>> +++ b/Makefile
>>> @@ -190,7 +190,7 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/i386/
>>> -e s/sun4u/sparc64/ \
>>> __export KBUILD_BUILDHOST := $(SUBARCH)
>>> __ARCH____________________ ?= $(SUBARCH)
>>> __CROSS_COMPILE__ ?=
>>> -CROSS_COMPILE__ ?= $(CONFIG_CROSS_COMPILE:"%"=%)
>>> +CROSS_COMPILE__ := $(shell grep CONFIG_CROSS_COMPILE .config | cut -d'"' -f2)
>>>
>>> __# Architecture as present in compile.h
>>> __UTS_MACHINE______ := $(ARCH)
>>> --
>>
>> Perhaps the "%"=% thing isn't supported with your version of make(1).
>> Which version are you using?
>
> My guess is that something expands $(CROSS_COMPILE) before make
> silentoldconfig generates include/config/auto.conf (which is where the
> makefile reads the CONFIG_* variables from). Tiago, can you try changing
> the $(shell ...) line to
>
> CROSS_COMPILE := $(shell ls include/config/auto.conf >&2; \
>    echo "CONFIG_CROSS_COMPILE $(CONFIG_CROSS_COMPILE) >&2; \
>    grep CONFIG_CROSS_COMPILE .config | cut -d'"'  -f2)
>
> and tell us what it prints?

I'm using GNU Make 3.81.

I think you missed a quote in echo..., I using:

CROSS_COMPILE := $(shell ls include/config/auto.conf >&2; \
    echo "CONFIG_CROSS_COMPILE" $(CONFIG_CROSS_COMPILE) >&2; \
    grep CONFIG_CROSS_COMPILE .config | cut -d'"'  -f2)

And the output:
$ make ARCH=arm O=../build

include/config/auto.conf
CONFIG_CROSS_COMPILE
  Using /usr/src/linux as source for kernel
  GEN     /usr/src/build/Makefile
  CHK     include/linux/version.h
  CHK     include/generated/utsrelease.h
make[2]: `include/generated/mach-types.h' is up to date.
  CALL    /usr/src/linux/scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  CC      arch/arm/mm/init.o

^C

Means that is nothing CONFIG_CROSS_COMPILE.

I agree with Andrew, directly grepping .config isn't the right thing to do.
I'd like to discuss a better solution.

--tm
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