Improving OpenJDK portability - platform specific C conditionals

[Kelly O'Hair]

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.

-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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