Re: compile for i86 on my PPC?

Sorry this has taken a while to respond to, but I wanted to have something useful to say.

I finally got this working pretty nicely. I can use the same code and makefile on either my tiPowerbook (PPC) or my loaner IntelMini, build and link and run the JNI lib, and it seems to work fine. This is good. Thanks to you guys for your help. Oh, yeah, I also figured out how to do it as a universal binary, which is a definite good.

(Our application, written in Java, loads a JNI lib that does math functions for us. One interesting feature of the JNI is that it compiles the user's inputted expressions into assembly language and executes that code on the fly. I had some headscratching to do when we started the Intel thing, since we could no longer assume that all Macs were running PPC (we already had x86 code generating for the Windows version). This made it necessary to rework the makefile, as well as changing around some of the preprocessor directives.)

Here is the compile/link part (which does the ppc/x86 universal thing I am so happy about, note that there are 2 -arch options):

$(TARGET): $(OBJECTS)

g++ -arch i386 -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -o $@ -dynamiclib -install_name $(DESTDIR)/$@ $^

strip -x $@

%.o: %.cpp

g++ -arch i386 -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -c -O2 -o $@ $^ -I /System/Library/Frameworks/JavaVM.framework/Headers

I had some trouble getting the output to work on the machine that the lib was not built on, so the lib build on the PPCPowerbook would not work on the IntelMini The solution was to be sure that the code generation line in the makefile used the universal SDK (MacOSX10.4u.sdk), as well as the liker line. I think this is the main lesson to learn: If you want a universal jni, compilable on either platform, amke sure you have the universal SDK included for both the compiler and linker.

Thanks to Eric and Kevin.

Paul Archibald

A society of sheep must in time beget a government of wolves.
-- Henry de Jouvenel

On May 5, 2006, at 1:22 PM, Eric Albert wrote:

Specifically, you'll want to pass the -arch flags and -isysroot to the compiler, like this:

$(TARGET): $(OBJECTS)
g++ -arch i386 -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -o $@ -dynamiclib -install_name $(DESTDIR)/$@ $^
strip -x $@

%.o: %.cpp
g++ -arch i386 -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk -c -O2 -o $@ $^ -I /System/Library/Frameworks/JavaVM.framework/Headers

Hope this helps,
Eric

On May 5, 2006, at 1:12 PM, Kevin Van Vechten wrote:

Yes, you can use the -arch argument with gcc or g++, i.e.:
g++ -arch i386 -arch ppc -arch ppc64 ...

Will build for all three architectures.

You'll need to be sure to build on a system with universal libraries so the link phase will succeed. I don't know whether they encompass JNI, but usually you'll want to use the 10.4u.SDK

For more details:

<http://developer.apple.com/technotes/tn2005/tn2137.html>

<http://developer.apple.com/opensource/buildingopensourceuniversal.html>

- Kevin

On May 5, 2006, at 1:05 PM, Paul Archibald wrote:

Our Java app uses a JNI lib for mathematical calculations. We build the JNI with GCC with a makefile.

Since we entering the IntelMac age, we need to target our JNIs to both the i86 and PPC architectures. I am doing it now by building the i86 JNI on an intelMini, and the PPC JNI on my PPC powerbook.

My question is this: can I build for a different architecture than that of the machine doing the compiling? I would like to be able to build both the PPC and i86 libs on whatever machine I have handy. Is there a g++ option to force which architecture is output? I am not very experienced with makefiles.

Here is part of my makefile:

$(TARGET): $(OBJECTS)
g++ -o $@ -dynamiclib -install_name $(DESTDIR)/$@ $^
strip -x $@

%.o: %.cpp
g++ -c -O2 -o $@ $^ -I /System/Library/Frameworks/JavaVM.framework/Headers

References:
	>compile for i86 on my PPC? (From: Paul Archibald <email@hidden>)
	>Re: compile for i86 on my PPC? (From: Kevin Van Vechten <email@hidden>)
	>Re: compile for i86 on my PPC? (From: Eric Albert <email@hidden>)