Re: [RFC PATCH 4/7] kconfig: support new special property shell=

[Masahiro Yamada]

2018-02-13 17:35 GMT+09:00 Arnd Bergmann <arnd@xxxxxxxx>:
> On Tue, Feb 13, 2018 at 2:53 AM, Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote:
>> On 02/12/2018 05:41 PM, Masahiro Yamada wrote:
>>> 2018-02-13 8:48 GMT+09:00 Randy Dunlap <rdunlap@xxxxxxxxxxxxx>:
>>>> On 02/12/2018 07:24 AM, Kees Cook wrote:
>>>>> On Mon, Feb 12, 2018 at 6:39 AM, Masahiro Yamada
>>>>> <yamada.masahiro@xxxxxxxxxxxxx> wrote:
>>>>
>>>>>>> (And in thinking about this, does Kconfig know the true $CC in use?
>>>>>>> i.e. the configured cross compiler, etc?)
>>>>>>
>>>>>> I was thinking of removing CONFIG_CROSS_COMPILE.
>>>>>>
>>>>>> A user can dynamically change CROSS_COMPILE from
>>>>>> "make menuconfig".
>>>>>
>>>>> Most builds I've seen implement cross compilers as an environment
>>>>> variable during all "make" invocations.
>>>>
>>>> I agree. I think you would break a bunch of build bots if you remove that.
>>>
>>>
>>> For clarification, I suggested to remove CONFIG_CROSS_COMPILE.
>>>
>>> The following code:
>>> https://github.com/torvalds/linux/blob/v4.16-rc1/Makefile#L315
>>> https://github.com/torvalds/linux/blob/v4.16-rc1/init/Kconfig#L58
>>>
>>> I hope build bots are not using this.
>>>
>>>
>>> Passing CROSS_COMPILE via the command line, environment
>>> is still supported.
>>
>> OK, I misunderstood.  That one can go away IMO.
>
> Removing it will break the workflow for some people in a minor way
> though. Could we have the top-level Makefile try to detect the
> CROSS_COMPILE? Instead of just using CC=gcc as the default,
> we could check for ${ARCH}!=`uname -m` and then see if $PATH
> contains a ${ARCH}-linux-gcc, ${ARCH}-elf-gcc or ${ARCH}-gcc.
>
> it will need slightly more complexity to deal with architectures
> that have different identifiers in linux and gcc, but I think it would
> be a nice feature anyway.
>
>      Arnd

Some architectures such as m68k, mips, etc.
do this in their arch/*/Makefile
by using $(call cc-cross-prefix, ...)

But, currently we do not do this globally.

It would be possible to do it, but it does not mean
backward-compatible with CONFIG_CROSS_COMPILE.


-- 
Best Regards
Masahiro Yamada