Improving OpenJDK portability - platform specific C conditionals

[Steve Poole]

On 19/07/11 00:20, Kelly O'Hair wrote:
>
> On Jul 18, 2011, at 4:00 PM, Steve Poole wrote:
>
>>
>>
>> Hi all,
>>
>> I want to start a discussion about the "right" way to deal with a 
>> particular aspect of C code portability - namely platform specific 
>> conditionals.
>>
>> In porting to AIX  we've frequently had to deal with  extending  
>> lines like:
>>
>> *#ifdef LINUX *
>>
>> to become
>>
>> *#if defined(LINUX) || defined(AIX)
>> *
>>
>> But that seems wrong - it doesn't aid OpenJDK portability except for 
>> one specific new platform.   It seems to me a better choice is not 
>> to  extend the ifdefs as above but  to move towards a capability 
>> based definition process.
>>
>> So have something like *#ifdef HAS_SPECIFIC_FUNCTION*   and then 
>> somewhere else have a build file the turns on *HAS_SPECIFIC_FUNCTION 
>> *if building on AIX or Linux.
>
> I always try and steer people this way, but it is hard to police the 
> entire code base.
>
>>
>> Ultimately of course this path takes you down to  supporting a   
>> ./configure  process...
>
> Or having some key setup.h file where these are defined, or defining 
> it in the makefiles. :^(
>
> We are heading toward a ./configure process in jdk8, just no specifics 
> yet.

That's good news -  this is important to me to get sorted out.   When 
you say "heading towards" does that mean
there is a discussion thread somewhere in OpenJDK where this is being 
discussed?   (There are so many mailing lists :-) )

>
> -kto
>
>>
>>
>> I assume this topic has come up before - what's the perceived wisdom 
>> for dealing with this problem?
>>
>>
>>
>> Cheers,
>>
>> Steve
>>
>>
>>
>

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