powerpc: 32BIT vs. 64BIT (PPC32 vs. PPC64)

[Michael Ellerman]

Masahiro Yamada <yamada.masahiro at socionext.com> writes:
> 2018-07-07 23:59 GMT+09:00 Randy Dunlap <rdunlap at infradead.org>:
>> On 07/07/2018 05:13 AM, Nicholas Piggin wrote:
>>> On Fri, 6 Jul 2018 21:58:29 -0700
>>> Randy Dunlap <rdunlap at infradead.org> wrote:
>>>
>>>> On 07/06/2018 06:45 PM, Benjamin Herrenschmidt wrote:
>>>>> On Thu, 2018-07-05 at 14:30 -0700, Randy Dunlap wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Is there a good way (or a shortcut) to do something like:
>>>>>>
>>>>>> $ make ARCH=powerpc O=PPC32 [other_options] allmodconfig
>>>>>>   to get a PPC32/32BIT allmodconfig
>>>>>>
>>>>>> and also be able to do:
>>>>>>
>>>>>> $make ARCH=powerpc O=PPC64 [other_options] allmodconfig
>>>>>>   to get a PPC64/64BIT allmodconfig?
>>>>>
>>>>> Hrm... O= is for the separate build dir, so there much be something
>>>>> else.
>>>>>
>>>>> You mean having ARCH= aliases like ppc/ppc32 and ppc64 ?
>>>>
>>>> Yes.
>>>>
>>>>> That would be a matter of overriding some .config defaults I suppose, I
>>>>> don't know how this is done on other archs.
>>>>>
>>>>> I see the aliasing trick in the Makefile but that's about it.
>>>>>
>>>>>> Note that arch/x86, arch/sh, and arch/sparc have ways to do
>>>>>> some flavor(s) of this (from Documentation/kbuild/kbuild.txt;
>>>>>> sh and sparc based on a recent "fix" patch from me):
>>>>>
>>>>> I fail to see what you are actually talking about here ... sorry. Do
>>>>> you have concrete examples on x86 or sparc ? From what I can tell the
>>>>> "i386" or "sparc32/sparc64" aliases just change SRCARCH in Makefile and
>>>>> 32 vs 64-bit is just a Kconfig option...
>>>>
>>>> Yes, your summary is mostly correct.
>>>>
>>>> I'm just looking for a way to do cross-compile builds that are close to
>>>> ppc32 allmodconfig and ppc64 allmodconfig.
>>>
>>> Would there a problem with adding ARCH=ppc32 / ppc64 matching? This
>>> seems to work...
>>
>> Yes, this mostly works and is similar to a patch (my patch) on my test machine.
>> And they both work for allmodconfig, which is my primary build target.
>>
>> And they both have one little quirk that is confusing when the build target
>> is defconfig:
>>
>> When ARCH=ppc32, the terminal output (stdout) is: (using O=PPC32)
>>
>> make[1]: Entering directory '/home/rdunlap/lnx/lnx-418-rc3/PPC32'
>>   GEN     ./Makefile
>> *** Default configuration is based on 'ppc64_defconfig'   <<<<< NOTE <<<<<
>> #
>> # configuration written to .config
>> #
>> make[1]: Leaving directory '/home/rdunlap/lnx/lnx-418-rc3/PPC32'
>>
>
>
> Maybe, we can set one of ppc32 defconfigs to KBUILD_DEFCONFIG
> if ARCH is ppc32 ?

We could, but as I said in another reply I'd rather we didn't play
tricks with ARCH.

I've merged a patch to add three new allmodconfig targets for ppc32,
ppc64le and ppc64_book3e:

  https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=54457&state=*


cheers