Re: Darwin universal binaries and LDFLAGS conundrum

[Peter O'Gorman]

On Wed, 2007-05-23 at 10:03 -0400, Martin-Gilles Lavoie wrote:
> Greetings
> 
> First, I'd like to apologize upfront for the sheer autoconf noob-ness  
> this post might impose on vets possibly on this list. But as luck  
> would have it, I seem to be stuck with the job of dealing with an  
> autoconf.ac script of ours wich doesn't seem to want to play nice  
> with the task at hand.
> 
> Full source code relating to the issue is available online at:
> 
>       http://www.oracle.com/technology/software/products/berkeley-db/ 
> index.html
> 
> To resume the problem, I need to build a Universal Binary (aka, PPC +  
> i386) library of BerkeleyDB. Now, normally, this is a simple task but  
> it seems Autoconfig is working against me.
> 
> At the strict minimum, I need to have the following flags set in the  
> generated makefile:
> 
>       CFLAGS=         -c $(CPPFLAGS) -O3 -isysroot /Developer/SDKs/ 
> MacOSX10.4u.sdk -arch i386 -arch ppc
>       LDFLAGS=        -Wl,-syslibroot,/Developer/SDKs/MacOSX10.4u.sdk
> 
> The problem is, whatever I set for LDFLAGS or CFLAGS in the .ac file  
> passed to autoconf, the output Makefile is invariably stripped down  
> to an empty LDFLAGS declaration and a CFLAGS devoid of the -isysroot  
> and -arch parameters.
> 
> Now being new to autoconf, I suspected I was doing something really  
> stupid until I stumbled onto this:
> 
>       http://www.nabble.com/Configure-Support-for-Mac-Universal-Builds- 
> t3635358.html

GNU libtool will pass -isysroot to the linker, I don't know if db uses
CFLAGS for linking, it should, if it does not,
LDFLAGS="-isysroot /Developer/SDKs/MacOSX10.4u.sdk" will work providing
that you are using the latest GNU libtool. The "linker" as far as GNU
libtool is concerned on Mac OS X is gcc, and gcc will translate
-isysroot to -syslibroot when calling ld.

Out of curiosity did you first compare config.h when doing a ./configure
on a ppc machine and an x86 machine without fat flags? Are they the
same? Are the assignments in the Makefiles the same? If you ever plan to
build 4-way fat, you will have to be more careful, pointer sizes are the
same on i386 and ppc, but things get more interesting when x86_64 and
ppc64 are added to the mix.

Peter

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