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

[Masahiro Yamada]

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...
>>
>> Thanks,
>> Nick
>
> 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 ?


ifeq ($(ARCH),ppc32)
   KBUILD_DEFCONFIG := (some reasonable 32bit machine _defconfig)
else
   KBUILD_DEFCONFIG := ppc64_defconfig
endif

ifeq ($(CROSS_COMPILE),)
    KBUILD_DEFCONFIG := $(shell uname -m)_defconfig
endif


> I expect that can be fixed also.  :)
>
> And the written .config file is indeed for 32BIT, not 64BIT.
>
> Thanks, Nick.
>
>> ---
>>  Makefile                               | 8 ++++++++
>>  arch/powerpc/Kconfig                   | 9 +++++++++
>>  arch/powerpc/platforms/Kconfig.cputype | 8 --------
>>  3 files changed, 17 insertions(+), 8 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index c5ce55cbc543..f97204aed17a 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -345,6 +345,14 @@ ifeq ($(ARCH),sh64)
>>         SRCARCH := sh
>>  endif
>>
>> +# Additional ARCH settings for powerpc
>> +ifeq ($(ARCH),ppc32)
>> +       SRCARCH := powerpc
>> +endif
>> +ifeq ($(ARCH),ppc64)
>> +       SRCARCH := powerpc
>> +endif
>> +
>>  KCONFIG_CONFIG       ?= .config
>>  export KCONFIG_CONFIG
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index 9f2b75fe2c2d..3405b1b122be 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -1,4 +1,13 @@
>>  # SPDX-License-Identifier: GPL-2.0
>> +
>> +config PPC64
>> +     bool "64-bit kernel" if "$(ARCH)" = "powerpc"
>> +     default "$(ARCH)" != "ppc32"
>> +     select ZLIB_DEFLATE
>> +     help
>> +       This option selects whether a 32-bit or a 64-bit kernel
>> +       will be built.
>> +
>>  source "arch/powerpc/platforms/Kconfig.cputype"
>>
>>  config PPC32
>> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
>> index e6a1de521319..f6e5d6ef9782 100644
>> --- a/arch/powerpc/platforms/Kconfig.cputype
>> +++ b/arch/powerpc/platforms/Kconfig.cputype
>> @@ -1,12 +1,4 @@
>>  # SPDX-License-Identifier: GPL-2.0
>> -config PPC64
>> -     bool "64-bit kernel"
>> -     default n
>> -     select ZLIB_DEFLATE
>> -     help
>> -       This option selects whether a 32-bit or a 64-bit kernel
>> -       will be built.
>> -
>>  menu "Processor support"
>>  choice
>>       prompt "Processor Type"
>>
>
>
> --
> ~Randy
> --
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-- 
Best Regards
Masahiro Yamada