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Subject: Re: [PATCH] MIPS: Loongson64: Give chance to build under !CONFIG_NUMA
 and !CONFIG_SMP
To:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>
References: <1606998772-5904-1-git-send-email-yangtiezhu@loongson.cn>
 <20201215132123.GA9201@alpha.franken.de>
 <3eb215e2-82ae-2834-2837-55f429027840@loongson.cn>
 <20201229163907.GA8519@alpha.franken.de>
Cc:     Huacai Chen <chenhc@lemote.com>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Youling Tang <tangyouling@loongson.cn>,
        Jinyang He <hejinyang@loongson.cn>
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
Message-ID: <5354959b-eacb-ff77-ab3d-dc0a6c89dc9f@loongson.cn>
Date:   Wed, 30 Dec 2020 08:54:34 +0800
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On 12/30/2020 12:39 AM, Thomas Bogendoerfer wrote:
> On Wed, Dec 16, 2020 at 10:44:23AM +0800, Tiezhu Yang wrote:
>> I have tested the following three configs on the Loongson platform:
>> (1) !NUMA and !SMP,
>> (2) !NUMA and SMP,
>> (3) NUMA and SMP,
>> everything is all right.
>>
>> But there exists the following build error under NUMA and !SMP:
>>
>>    CC      arch/mips/kernel/asm-offsets.s
>> In file included from ./include/linux/gfp.h:9:0,
>>                   from ./include/linux/xarray.h:14,
>>                   from ./include/linux/radix-tree.h:19,
>>                   from ./include/linux/fs.h:15,
>>                   from ./include/linux/compat.h:17,
>>                   from arch/mips/kernel/asm-offsets.c:12:
>> ./include/linux/topology.h: In function ‘numa_node_id’:
>> ./include/linux/topology.h:119:2: error: implicit declaration of function
>> ‘cpu_logical_map’ [-Werror=implicit-function-declaration]
>>    return cpu_to_node(raw_smp_processor_id());
>>    ^
>> cc1: some warnings being treated as errors
>> scripts/Makefile.build:117: recipe for target
>> 'arch/mips/kernel/asm-offsets.s' failed
>> make[1]: *** [arch/mips/kernel/asm-offsets.s] Error 1
>> arch/mips/Makefile:396: recipe for target 'archprepare' failed
>> make: *** [archprepare] Error 2
>>
>> I find a patch to fix this kind of build errors [1], but it seems
>> meaningless.
>>
>> According to the NUMA and SMP description in arch/mips/Kconfig,
>> we will use only one CPU of a multiprocessor machine if !SMP,
>> on single node systems leave NUMA disabled.
>>
>> So I think there is no need to use NUMA if !SMP, and also we should
>> make NUMA depend on SMP to avoid build errors.
> ok, but compiling IP27 with your patch gives
>
> WARNING: unmet direct dependencies detected for NUMA
>    Depends on [n]: SYS_SUPPORTS_NUMA [=y] && SMP [=n]
>    Selected by [y]:
>    - SGI_IP27 [=y] && <choice>
>
> WARNING: unmet direct dependencies detected for NUMA
>    Depends on [n]: SYS_SUPPORTS_NUMA [=y] && SMP [=n]
>    Selected by [y]:
>    - SGI_IP27 [=y] && <choice>
>
> WARNING: unmet direct dependencies detected for NUMA
>    Depends on [n]: SYS_SUPPORTS_NUMA [=y] && SMP [=n]
>    Selected by [y]:
>    - SGI_IP27 [=y] && <choice>
>
> If I use "select SMP" instead both ip27 and loongson64 compile.
>
> If you are ok with this change, I'll change it while appling your
> patch.

No problem, looks good to me, thank you very much.

Thanks,
Tiezhu
>
> Thomas.
>