linux-kernel - Re: Linux kernel cross-compilers

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Message-ID: <CAMo8BfK8pwMy7MPqrhRH2XPjfgu+H2pGhxBjbxKqnHwficKNFw@mail.gmail.com>
Date:	Fri, 16 Aug 2013 23:09:38 +0400
From:	Max Filippov <jcmvbkbc@...il.com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Chris Zankel <chris@...kel.net>
Subject: Re: Linux kernel cross-compilers

On Fri, Aug 16, 2013 at 7:43 PM, Guenter Roeck <linux@...ck-us.net> wrote:
> On 08/16/2013 02:45 AM, Max Filippov wrote:
>>>>
>>>> Guenter,
>>>> can you share a complete build log with V=1?
>>>>
>>>
>>> http://roeck-us.net/linux/logs/make.xtensa.log.bad
>>> http://roeck-us.net/linux/logs/make.xtensa.log.ok
>>>
>>> Key difference: the failing command in the bad case is
>>>          xtensa-linux-objcopy -O elf32-xtensa-le
>>> and in the good case
>>>          xtensa-linux-objcopy -O elf32-xtensa-be
>>>
>>> Same compiler (4.6.3 from kernel.org), same configuration file, same
>>> command
>>> line.
>>> Configuration file is generated from defconfig, and the resulting .config
>>> file
>>> is the same in both cases.
>>>
>>> If I execute make and expicitly set BIG_ENDIAN=1 on the failing system as
>>> parameter to it,
>>> it works fine. If I set BIG_ENDIAN=0 on the passing system, it fails.
>>>
>>> I am puzzled. Guess there must be something different, but I have no idea
>>> what it might be.
>>
>>
>> What is the output of
>>
>> echo -e __XTENSA_EB__ | xtensa-linux-gcc -E -
>>
>> on the failing system?
>>
> It is "1", but that let me pinpoint the problem.
>
> On the failing system, the version of echo executed by make does
> not understand the "-e" option. Thus, when running
> arch/xtensa/boot/Makefile,
> "echo -e __XTENSA_EB__" returns "-e __XTENSA_EB__", which doesn't compile,
> and BIG_ENDIAN ends up being 0. So the compiler is completely innocent.
>
> I found out the root source: SHELL is set the /bin/sh, which on the failing
> system points to /bin/dash (default in Ubuntu, or at least it used to be).
> dash apparently has a built-in version of echo which does not understand
> '-e'.
> Oh well.

Cool. OTOH I don't think that we need to -e to output __XTENSA_EB__.
Will send a patch for that.

-- 
Thanks.
-- Max
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