Re: [2.6 patch] ia64: let NUMA select SMP

Mike Travis
2008-04-25T12:50:49Z

Adrian Bunk wrote:
> On Thu, Apr 24, 2008 at 05:25:06PM -0700, Luck, Tony wrote:
>>>> Build fix for CONFIG_NUMA=y && CONFIG_SMP=n
>>>> ...
>>> Why is this an allowed configuration on ia64?
>> It shows up in allnoconfig ... probably because some
>> bit of Kconfig forces NUMA=y.
>
> allnoconfig results in CONFIG_IA64_GENERIC=y, which in turn selects NUMA.
>
> What about the patch below instead?
>
>> I can't imagine that it is ever a useful combination ... except to
>> find places in the code where people have:

Though highly unlikely, it is possible to have multiple memory nodes
without having multiple cpus -- at least in theory. In this specific
case it's nonsensical because the scheduler is grouping cpus by node.

Thanks,
Mike

>>
>> #if defined(CONFIG_SMP)
>> ...
>> #else
>>
>> #if defined(CONFIG_NUMA) // !!! SMP=n, NUMA code???
>> ...
>> #endif
>> #endif
>>
>>
>> Which is what happened, and is being fixed, here.
>
> If it isn't a useful combination such code makes no sense.
>
>> -Tony
>
> cu
> Adrian
>
>
> <-- snip -->
>
>
> CONFIG_NUMA=y, CONFIG_SMP=n isn't a useful combination, so let NUMA
> select SMP.
>
> Signed-off-by: Adrian Bunk <bunk@kernel.org>
>
> ---
> a94d43a82a3c5a95c82b9688e5adebca6dcb7acb diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
> index cd13e13..19e8167 100644
> --- a/arch/ia64/Kconfig
> +++ b/arch/ia64/Kconfig
> @@ -387,6 +387,7 @@ config NUMA
> bool "NUMA support"
> depends on !IA64_HP_SIM && !FLATMEM
> default y if IA64_SGI_SN2
> + select SMP
> select ACPI_NUMA if ACPI
> help
> Say Y to compile the kernel to support NUMA (Non-Uniform Memory
>