plans for 64bit support

[Ryan Schmidt]

On Dec 9, 2007, at 14:43, Daniel Oberhoff wrote:

> Now that Leopard is out and already at 10.5.1 will macports be  
> supporting 64bit libraries? It's just I need 64bit in my octave  
> installation. I pull my octave from octave.org's cvs, but it needs  
> quite a lot of support libraries. From what I gather it should be  
> possible on Leopard to build fat libraries, i.e. ones that contain  
> 64 and 32 bit code (i think it works using -arch x84_64 -arch i686  
> as gcc flags). Or will this be left to the separate ports?

MacPorts is supposed to build libraries for whatever system it's  
running on. So I would have thought that if you're on a 64-bit Intel  
system, it should build 64-bit Intel libraries. Is it building 32-bit  
Intel libraries for you?

We have the +universal variant for building 2-way (32-bit, Intel and  
PowerPC) universal binaries. We are still in the process of getting  
this to work with many of the ports. It could be changed to build 4- 
way (32-bit and 64-bit, Intel and PowerPC) universal binaries. This  
should be possible on Tiger too, as far as I know. It won't fix any  
ports that are having trouble building 2-way universal binaries. Not  
sure if it would mess up any ports that are already working. Are all  
the ports that you need already working as 2-way universal binaries?

I haven't heard anyone suggest building libraries that contain 32-bit  
and 64-bit code for just one processor family before (in relation to  
MacPorts). It would of course be possible, but I think it would make  
most sense to continue along our current path: software should be  
default install for the architecture you're on, and if you need  
multiple architectures, then you need the +universal variant.

It has been said before that maybe 64-bit binaries aren't all that  
helpful, but the Ars Technica review of Leopard explains that while  
64-bit binaries aren't that helpful on the PowerPC architecture, they  
really are quite good for secondary reasons on the Intel  
architecture. The 32-bit Intel architecture has often been called  
inferior to the 32-bit PowerPC architecture, but the 64-bit Intel  
architecture seems to fix many of the issues. Also, maybe Leopard  
being a full 64-bit system makes 64-bit binaries more relevant.

Perhaps we could do 4-way universal binaries only when MacPorts is  
running on Leopard.... but that might be a bad idea, since only  
people running Leopard could  then develop and test this.

We could introduce a new automatic variant... +universal4?  
+universal64? People could test with this new variant and if any  
problems are encountered it would not prevent anyone from using the  
existing 2-way 32-bit +universal variant. I'm wary of this though...  
I wouldn't want, say, "universal64" directives to start appearing in  
portfiles, if we want to eventually fold +universal64 into +universal.

Just some thoughts off the top of my head.