Re: [PATCH] mm: add config NUMA stub to all architectures

Re: [PATCH] mm: add config NUMA stub to all architectures

[Randy Dunlap]

On 02/19/2012 09:01 AM, Geert Uytterhoeven wrote:
> On Fri, Feb 17, 2012 at 21:30, Andrew Morton<akpm@linux-foundation.org>  wrote:
>> On Fri, 17 Feb 2012 16:08:15 +0400
>> Konstantin Khlebnikov<khlebnikov@openvz.org>  wrote:
>>
>>> Config NUMA must be defined for all architectures,
>>> otherwise IS_ENABLED(CONFIG_NUMA) does not work.
>>> Some arch-specific Kconfig already has this stub.
>>> This patch adds it to all remaining.
>>
>> It would be better to teach IS_ENABLED() to handle this situation.  I
>> don't think there's a way of doing this with cpp :(
>>
>> This limitation makes IS_ENABLED pretty dangerous, doesn't it?  It
>> makes it very easy to introduce build breakage with unexpected Kconfig
>> combinations.
>
> Indeed. Recently I discovered IS_ENABLED() and started recommending it
> to people for new code. But now I've seen the CONFIG_NUMA breakage,
> I no longer think this is a good recommendation.


adding Michal & linux-kbuild to cc: list.

-- 
~Randy

Re: [PATCH] mm: add config NUMA stub to all architectures

[Arnaud Lacombe]

Hi,

On Sun, Feb 19, 2012 at 1:12 PM, Randy Dunlap <rdunlap@xenotime.net> wrote:
> On 02/19/2012 09:01 AM, Geert Uytterhoeven wrote:
>>
>> On Fri, Feb 17, 2012 at 21:30, Andrew Morton<akpm@linux-foundation.org>
>>  wrote:
>>>
>>> On Fri, 17 Feb 2012 16:08:15 +0400
>>> Konstantin Khlebnikov<khlebnikov@openvz.org>  wrote:
>>>
>>>> Config NUMA must be defined for all architectures,
>>>> otherwise IS_ENABLED(CONFIG_NUMA) does not work.
>>>> Some arch-specific Kconfig already has this stub.
>>>> This patch adds it to all remaining.
>>>
>>>
>>> It would be better to teach IS_ENABLED() to handle this situation.  I
>>> don't think there's a way of doing this with cpp :(
>>>
>>> This limitation makes IS_ENABLED pretty dangerous, doesn't it?  It
>>> makes it very easy to introduce build breakage with unexpected Kconfig
>>> combinations.
>>
>>
>> Indeed. Recently I discovered IS_ENABLED() and started recommending it
>> to people for new code. But now I've seen the CONFIG_NUMA breakage,
>> I no longer think this is a good recommendation.
>
> adding Michal & linux-kbuild to cc: list.
>
I do not really see any way to fix this, beside having a unique
architecture-wide configuration namespace :/

 - Arnaud

Re: [PATCH] mm: add config NUMA stub to all architectures

[Michal Marek]

On 20.2.2012 00:21, Arnaud Lacombe wrote:
> On Sun, Feb 19, 2012 at 1:12 PM, Randy Dunlap <rdunlap@xenotime.net> wrote:
>> On 02/19/2012 09:01 AM, Geert Uytterhoeven wrote:
>>>
>>> On Fri, Feb 17, 2012 at 21:30, Andrew Morton<akpm@linux-foundation.org>
>>>  wrote:
>>>> It would be better to teach IS_ENABLED() to handle this situation.  I
>>>> don't think there's a way of doing this with cpp :(
>>>>
>>>> This limitation makes IS_ENABLED pretty dangerous, doesn't it?  It
>>>> makes it very easy to introduce build breakage with unexpected Kconfig
>>>> combinations.
>>>
>>>
>>> Indeed. Recently I discovered IS_ENABLED() and started recommending it
>>> to people for new code. But now I've seen the CONFIG_NUMA breakage,
>>> I no longer think this is a good recommendation.
>>
>> adding Michal & linux-kbuild to cc: list.
>>
> I do not really see any way to fix this, beside having a unique
> architecture-wide configuration namespace :/

Having a single namespace, or less ambitiously, having less
arch-specific config symbol definitions, would be a plus. IS_ENABLED
requiring the symbol to be defined is not bad per se, it prevents typos.

Michal