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Subject: Re: arch/mips/include/asm/mach-ip27/topology.h:19:7: error: implicit
 declaration of function 'hub_data'
To:     Mike Rapoport <rppt@linux.ibm.com>,
        kernel test robot <lkp@intel.com>
Cc:     linux-kernel@vger.kernel.org, Paul Burton <paul.burton@mips.com>,
        Thomas Bogendoerfer <tbogendoerfer@suse.de>,
        linux-mips@vger.kernel.org
References: <202008040108.xTarUIe8%lkp@intel.com>
 <20200803194910.GC72435@linux.ibm.com>
From:   Joshua Kinard <kumba@gentoo.org>
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Date:   Mon, 3 Aug 2020 19:58:54 -0400
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On 8/3/2020 15:49, Mike Rapoport wrote:
> Hi,
> 
> On Tue, Aug 04, 2020 at 01:39:14AM +0800, kernel test robot wrote:
>> Hi Mike,
>>
>> FYI, the error/warning still remains.
>>
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> head:   bcf876870b95592b52519ed4aafcf9d95999bc9c
>> commit: 397dc00e249ec64e106374565575dd0eb7e25998 mips: sgi-ip27: switch from DISCONTIGMEM to SPARSEMEM
>> date:   10 months ago
>> config: mips-randconfig-r032-20200803 (attached as .config)
>> compiler: mips64-linux-gcc (GCC) 9.3.0
>> reproduce (this is a W=1 build):
>>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>         chmod +x ~/bin/make.cross
>>         git checkout 397dc00e249ec64e106374565575dd0eb7e25998
>>         # save the attached .config to linux build tree
>>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@intel.com>
>>
>> All errors (new ones prefixed by >>):
>>
>>    In file included from arch/mips/include/asm/topology.h:11,
>>                     from include/linux/topology.h:36,
>>                     from include/linux/gfp.h:9,
>>                     from include/linux/slab.h:15,
>>                     from include/linux/crypto.h:19,
>>                     from include/crypto/hash.h:11,
>>                     from include/linux/uio.h:10,
>>                     from include/linux/socket.h:8,
>>                     from include/linux/compat.h:15,
>>                     from arch/mips/kernel/asm-offsets.c:12:
>>    arch/mips/include/asm/mach-ip27/topology.h:25:39: error: 'MAX_COMPACT_NODES' undeclared here (not in a function)
>>       25 | extern unsigned char __node_distances[MAX_COMPACT_NODES][MAX_COMPACT_NODES];
>>          |                                       ^~~~~~~~~~~~~~~~~
>>    include/linux/topology.h: In function 'numa_node_id':
>>>> arch/mips/include/asm/mach-ip27/topology.h:16:27: error: implicit declaration of function 'cputonasid' [-Werror=implicit-function-declaration]
>>       16 | #define cpu_to_node(cpu) (cputonasid(cpu))
>>          |                           ^~~~~~~~~~
> 
> This happens when randconfig disables NUMA and has SGI_IP27 enabled.
> Before switch from discontigmem to sparsemem, there always was
> CONFIG_NEED_MULTIPLE_NODES=y because it was selected by DISCONTIGMEM.
> Without DISCONTIGMEM it is possible to have SPARSEMEM without NUMA for
> SGI_IP27 and as many things there rely on custom node definition, the
> build breaks.
> 
> I don't remember small Origin or Onyx systems so I think it would be
> reasonable to make SGI_IP27 to select NUMA. If the below patch makes
> sense I'll resend it formally.
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 6fee1a133e9d..a7e40bb1e5bc 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -678,6 +678,7 @@ config SGI_IP27
>  	select SYS_SUPPORTS_NUMA
>  	select SYS_SUPPORTS_SMP
>  	select MIPS_L1_CACHE_SHIFT_7
> +	select NUMA
>  	help
>  	  This are the SGI Origin 200, Origin 2000 and Onyx 2 Graphics
>  	  workstations.  To compile a Linux kernel that runs on these, say Y

NUMA is really only needed if you have more than one nodeboard for the Onyx2
or Origin2000 systems.  If you just have a single Origin 200 system, you
want to turn NUMA off.  I happen to have both a single Origin 200 system and
an Onyx2 w/ two nodeboards.  Haven't fired them up recently on modern
kernels, though.

I can't think of a good workaround off the top of my head for this case.
NUMA shouldn't hurt an Origin 200, but I recall Ralf once telling me it does
introduce slowdown at some points due to checks for other nodes being done
when we know there can't physically be any more (exception: dual Origin
200's hooked together via CrossTown cables).

-- 
Joshua Kinard
Gentoo/MIPS
kumba@gentoo.org
rsa6144/5C63F4E3F5C6C943 2015-04-27
177C 1972 1FB8 F254 BAD0 3E72 5C63 F4E3 F5C6 C943

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