plans for 64bit support

[Weissmann Markus]

On 12.12.2007, at 12:31, Daniel Oberhoff wrote:

> ---------- Forwarded message ----------
> From: Daniel Oberhoff <daniel at danieloberhoff.de>
> Date: Dec 12, 2007 12:29 PM
> Subject: Re: plans for 64bit support
> To: Weissmann Markus <mww at macports.org>
>
>
> [...]
>
> we put some research into this during GSOC this year: It's quite hard
> to come up with a magic lipo for everything as it is necessary to
> combine not only binaries (thats the easy part) but also stuff like
> header files (also easy), heap images of interpreters, scripting
> language programs, etc. -- which can get practically impossible.
>
> We could enable four-way builds for (probably) all ports that we can
> build universal right now, but there is currently no way of saying
> "no ppc64 please" (etc.) in a port (and no tests/experience on what
> exactly will be necessary).
>
> Hmm, but that would mean I always have to build 4 times and waste  
> lots of space and time I will never ever need (i.e. on my intel mac  
> I will never use ppc binaries). Are ppc+interl universals so  
> important? After all macports is more of a local compile and use  
> thing than about binary distribution, right?
>

Well, our ultimate goal here would be to have these 4-way universal  
builds as packages... but don't hold your breath for this to happen:  
There is a lot of work to be done for this.
Regarding the space and time issue: Yes, building universal will take  
roughly 4 times as long, but not take 4 times the space: The most  
space is normally consumed by data files like documentation,  
pictures, icons, etc.


>  >> Alternatively maybe have two macports trees, one with 64bit, one
> >> with 32bit. Kinda like those lib64 dirs on some linux flavours. Is
> >> that possible right now?
> >
> > You're talking about two collections of port binaries, presumably?
> > Since we don't have any binaries at this point, or any 64-bit
> > builds, anything's possible, of course. Is it wise to have 64-bit-
> > only binaries? I wouldn't have thought so but I really have no idea.
> >
> > If you mean, is it possible to have 64-bit builds go into lib64
> > instead of lib, then I would say if that's not the default for the
> > software already, it would be a rather large hassle to fix every
> > portfile to do this, wouldn't you say? And why is this better than
> > a single all-encompassing superuniversal library installed in the
> > normal expected location?
> >
>
> you could always pass a "-arch x86_64" (or "-arch ppc64") to the
> cflags/cxxflags/.. manually if you desperately need 64 bit support,
> e.g.:
> $> port -d install readline configure.cflags="-O2 -arch x86_64"
> (no idea if that one compiles though)
>
> If you want to make some tests with four-way universal builds,
> replace each occurrence (there are 3) of "-arch i386 -arch ppc" in /
> opt/local/share/macports/Tcl/port1.0/portconfigure.tcl with "-arch
> i386 -arch x86_64 -arch ppc -arch ppc64".
> We are of course interested in your results... ;)
>
> Hmm, no, this went down the wrong path. Let me clarify: Someone  
> before said that on Leopard macports would automatically build 64  
> bit binaries. Now I was wondering if
>
> a) I could prevent this (i.e. have it build 32bit as before)
> b) If I could have two completely independent macports repos on my  
> disk, one built 32bit and one 64bit. This would be ideal since most  
> everyday stuff is 32bit, and only some libs and stuiff are needed  
> for 64. I would go as far as saying this latter option would be the  
> best solution (less hassle than doing universal builds and better  
> controllable),
>
> for the 32/64 bit versions I would really like this supported in  
> macports properly, and not have to fiddle with build flags... I  
> would like a repo-constant switch for this. I.e. some repo (I refer  
> to repo as a local macports install tree, i.e. what is usually  
> under /opt/local) would be set up as 64bit and always be 64bit from  
> there on (i.e. update, install and all when on this repo do 64bit  
> builds). And another would be 32bit. One could do the same for ppc.  
> I think real universal binaries are only ever needed for  
> distribution, and then one can always go and lipo things by hand.
>
> So is this kind of repo-based architecture selection possible. And  
> the installation of multiple macports repos? If not I would even  
> help make it possible if someone gets me started :).
>

By default the Apple compilers will produce 32 bit binaries, so if  
you don't do anything, you'll end up with 32 bit ppc or i386  
binaries. We currently don't have a switch to enable 64 bit binaries,  
so no: "just" installing MacPorts a 2nd time isn't getting you  
anywhere near there.
I'd recommend (for now) to hack the portconfigure.tcl [1] file and  
replace "-arch i386 -arch ppc" with "-arch i386 -arch x86_64", then  
build the stuff you need with "+universal".
For more awesomeness to happen sooner, I'd advice to start hacking  
port(1) with us... ;)


Regards,

-Markus

---
Dipl. Inf. (FH) Markus W. Weissmann
http://www.mweissmann.de/
http://www.macports.org/