plans for 64bit support

[Ryan Schmidt]

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On Dec 11, 2007, at 04:30, Keith J. Schultz wrote:

> Am 11.12.2007 um 09:50 schrieb Ryan Schmidt:
>
>> On Dec 11, 2007, at 02:35, Daniel Oberhoff wrote:
>>
>>> Am 10.12.2007 um 01:33 schrieb 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.
>>>
>>> Hmm, ok. That makes sense, since I upgraded with an installed  
>>> macports base. I suppose I should really reinstall all then,  
>>> since otherwise I will end up with a crazy mix?
>>
>> Yes, if you're moving from one architecture to another (G4->G5,  
>> PPC->Intel, 32-bit->64-bit, etc.) you should really throw away  
>> your old MacPorts (saving any conf files or databases or other  
>> data) and rebuild all your ports.
>>
>>> Though, per default on Leopard compilation seems to be 32 bit.  
>>> When you just compile something without further options pointer  
>>> size is 32bit. Only when you specify -arch x86_64 or -m64 do you  
>>> get 64bit.
>>
>> Ah, I see. I didn't know. I haven't had a 64-bit machine.
>>
>>> So it would really make sense to have both (but not ppc). So I  
>>> would vote for an autamatic variant to get intel only 32/64bit.
>>
>> So by default we build 32-bit binaries for the host architecture.  
>> And we have a +universal variant for building 32-bit binaries for  
>> both architectures. You want an additional variant for building  
>> fat 32-bit and 64-bit Intel binaries. Do we then also need a  
>> separate variant for building fat 32-bit and 64-bit PowerPC  
>> binaries? And what about a fat universal variant with all 4  
>> options? This proliferation of variants is what I want to avoid.  
>> Most users will not need it and it will confuse some of them. It's  
>> much extra work for some portfile authors, because some software  
>> (rather a lot, actually) does not build successful universal  
>> binaries using the simple tricks, and much more work is required  
>> to build universal. See for example the openssl port (which, to  
>> build universal, you'll have to back-date to version 0.9.8e  
>> because of bug #12911) which goes through crazy hoops to build  
>> first for one architecture, then the other, then lipo them  
>> together. Similar (though perhaps not identical) hoops would have  
>> to be gone through for fat binaries or 4-way binaries. Well, that  
>> is until MacPorts base grows some universal-build helpers. (I  
>> still really think MacPorts base should have an easy way to build  
>> a port multiple times, once for each architecture, and lipo it  
>> together, automatically, selected with just a single line in the  
>> portfile).
>>
>>
>> Why, by the way, do you need 64-bit octave? Just curious.
>
> Hi Everybody,
>
> 	Why would someone with a Intel or PowerPC want to build a  
> universal for a port.
> 	I mean it is build on one machine and is used on one machine. I  
> can understand
> 	the variants for Intel and PowerPC as well as the need for 32 or  
> 64 bit variants,
> 	but universal no way.
>
> 	Yes, a port author will want to test and build the different  
> variants, but why universal.
> 	I mean ports does not need unversal variants on the pure unix  
> side. Cocoa Apps is a different
> 	matter, but since they are build on the host machine we could do  
> with out it. So we have:
> 		1) Intel + 64
> 		2) Intel + 32
> 		3) PowerPC + 64 (G5 only)
> 		4) PowerPC + 32
>
>  	I believe that which version to build can be guess by looking at  
> the CPU. Should not autoconfig
> 	handle that?
>
> 	regards
> 		Keith.

I don't think now is the time to second-guess MacPorts's universal  
support, which has been around since r22313 10 months ago and is  
being improved on a port by port basis as problems are discovered.  
MacPorts's universal support is explained in the first item of the FAQ:

http://trac.macports.org/projects/macports/wiki/FAQ#IsMacPortsUniversal

True, most users do not need universal ports. But some do. Some  
install MacPorts on an external hard drive that they might connect to  
either a PowerPC- or an Intel-based Mac. Or some users may install  
MacPorts on their current PowerPC Mac, then later use Migration  
Assistant to migrate the content of their hard drive to a newly- 
bought Intel-based Mac. Users who have installed +universal versions  
of all ports can continue unhindered, while those who did not will  
have to blow away their MacPorts installation, reinstall MacPorts and  
re-build all their ports.

A goal of MacPorts is to eventually distribute binaries of ports,  
rather than make everyone compile things themselves. It would be  
inconvenient to have to maintain separate PowerPC and Intel binaries,  
hence the desire to have universal binaries so we can have just a  
single binary download for each port. If and when that ever happens.

Therefore, we certainly don't want to now increase the number of  
binary ways the software can be built, so we don't want separate ways  
to build fat Intel or fat PowerPC binaries. Rather, I would suggest,  
as I suggested before, that we should have the default, which builds  
for the local host architecture only, which most users today will  
use, and we should have +universal, as we do now, but which can be  
extended to support all 4 binary types that one might conceivably  
want, if indeed 64-bit binaries are useful to have.

As far as I know, autoconf was conceived without having considered  
multiple-architecture binaries, so I don't know that it's going to be  
any help in building fat or universal binaries.