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Subject: Re: arch/mips/include/asm/mach-ip27/topology.h:19:7: error: implicit
 declaration of function 'hub_data'
To:     Joshua Kinard <kumba@gentoo.org>,
        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>
 <6a37284b-cbdb-36c8-b258-1a47e6c029ef@gentoo.org>
From:   Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-ID: <d3d246c4-e1dd-5d8d-a8c0-23f9cfe878fd@flygoat.com>
Date:   Tue, 4 Aug 2020 19:34:39 +0800
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在 2020/8/4 上午7:58, Joshua Kinard 写道:
> 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).
Then something like this would be more reasonable:

diff --git a/arch/mips/include/asm/mach-ip27/topology.h 
b/arch/mips/include/asm/mach-ip27/topology.h
index d66cc53feab8..8976b9a20bdc 100644
--- a/arch/mips/include/asm/mach-ip27/topology.h
+++ b/arch/mips/include/asm/mach-ip27/topology.h
@@ -13,6 +13,7 @@ struct cpuinfo_ip27 {

  extern struct cpuinfo_ip27 sn_cpu_info[NR_CPUS];

+#ifdef CONFIG_NUMA
  #define cpu_to_node(cpu)       (cputonasid(cpu))
  #define cpumask_of_node(node)  ((node) == -1 ?                         \
                                  cpu_all_mask :                         \
@@ -25,6 +26,10 @@ extern int pcibus_to_node(struct pci_bus *);
  extern unsigned char __node_distances[MAX_NUMNODES][MAX_NUMNODES];

  #define node_distance(from, to) (__node_distances[(from)][(to)])
+#else
+#define cpu_to_node(cpu)       0
+#define cpumask_of_node(node)  cpu_present_mask
+#endif

  #include <asm-generic/topology.h>

- Jiaxun
>