Hi, I wrote this reply some time ago, but now it&#39;s also relevant:<br><br><div class="gmail_quote">On Thu, Oct 22, 2009 at 11:13 AM, Vladimir Prus <span dir="ltr">&lt;<a href="mailto:ghost@cs.msu.su">ghost@cs.msu.su</a>&gt;</span> wrote:<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
I am still trying to figure the right magic to disable -ppc64 when<br>
using 10.6 SDK. Am I right that ppc64 is not supported with 10.6<br>
regardless of whether you are building a fat library, or not? In other<br>
words, does explicit<br>
<br>
        address-model=64 architecture=power<br>
<br>
have any chance of working?<br><br></blockquote><div>short answer: no</div><div>long answer: (sorry if this is already known)</div><div><br></div><blockquote class="gmail_quote" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex; ">
I second the request for a patch for this issue to get into the next release, at least the portion of the patch that removes the -m64 option from the command line.<br></blockquote><div><br></div><div>the &quot;at least the -m64 portion&quot; is important, since for the other portion of the patch, the statement &quot;gcc-4.2 from the Developer Tools package Apple released for Snow Leopard cannot compile -arch ppc64 for any target version of OS X&quot; is not true. I have done some experimentation quite some time ago and while I don&#39;t remember for sure, I think the combination of _both_ gcc version (selected on command-line by typing g++-4.0 or g++-4.2) and the MacOSX10.&lt;version&gt;.sdk (selected with bjam via macosx-version and macosx-version-min, and with bar command-line by -mmacosx-version-min=10.&lt;version&gt; and -isysroot /Developer/SDKs/MacOSX10.&lt;version&gt;.sdk) determines whether gcc-4.2 is able to compile -arch ppc64 binary.</div>
<div><br></div><div>Try it yourself with a minimal test.cpp of your own making, including a few standard header files:</div><div><br></div><div>This works on Snow Leopard, because there is nothing really snow-leopard specific to it - everything is used like if you were compiling on Leopard with no special flags:</div>
<div>g++-4.2 -mmacosx-version-min=10.5 -isysroot /Developer/SDKs/MacOSX10.5.sdk/ -arch ppc64 test.cpp -o test</div><div><br></div><div>The following does not work (even for -arch i386), since GCC 4.2 was not available on Tiger, and so GCC&#39;s internal headers for the 4.2 version are not available in the Tiger (10.4) SDK:</div>
<div><div>g++-4.2 -mmacosx-version-min=10.4 -isysroot /Developer/SDKs/MacOSX10.4u.sdk/ -arch ppc64 test.cpp -o test</div><div>test.cpp:1:20: error: iostream: No such file or directory</div><div>test.cpp:2:19: error: cstdlib: No such file or directory</div>
<div><br></div><div>If you do the above with a file that does not use any C++ standard headers (i.e. int main(){ return 0; }), it does produce an executable that works!</div><div><br></div><div>And this does not work, since on Snow Leopard, GCC 4.2 is available along with its internal headers, but the internal headers specially for -arch ppc64 are missing, since Snow Leopard itself does not run on ppc, and ppc is probably not supported via the Rosetta ppc emulator for Intel processors:</div>
<div><div>g++-4.2 -mmacosx-version-min=10.6 -isysroot /Developer/SDKs/MacOSX10.6.sdk/ -arch ppc64 test.cpp -o test</div><div>In file included from test.cpp:1:</div><div>/Developer/SDKs/MacOSX10.6.sdk//usr/include/c++/4.2.1/iostream:44:28: error: bits/c++config.h: No such file or directory</div>
<div>In file included from /Developer/SDKs/MacOSX10.6.sdk//usr/include/c++/4.2.1/ios:43,</div><div>                 from /Developer/SDKs/MacOSX10.6.sdk//usr/include/c++/4.2.1/ostream:45,</div><div>                 from /Developer/SDKs/MacOSX10.6.sdk//usr/include/c++/4.2.1/iostream:45,</div>
<div>                 from test.cpp:1:</div><div>/Developer/SDKs/MacOSX10.6.sdk//usr/include/c++/4.2.1/iosfwd:45:29: error: bits/c++locale.h: No such file or directory</div><div>... (much more lines)</div></div></div><div>
<br></div><div><br></div><div>the bits/* files are present in a platform-specific internal header, and ppc64 is missing:</div><div><div>find /Developer/SDKs/MacOSX10.6.sdk/usr/include/c++/4.0.0/ -name c++locale.h</div><div>
/Developer/SDKs/MacOSX10.6.sdk/usr/include/c++/4.0.0//i686-apple-darwin10/bits/c++locale.h</div><div>/Developer/SDKs/MacOSX10.6.sdk/usr/include/c++/4.0.0//powerpc-apple-darwin10/bits/c++locale.h</div><div>/Developer/SDKs/MacOSX10.6.sdk/usr/include/c++/4.0.0//x86_64-apple-darwin10/bits/c++locale.h</div>
<div><br></div><div>ppc64 bits/* files are present in the 10.5 and 10.4u SDK.</div><div><br></div><div>I tried now the same experiment with g++-4.0: works for 10.4u and 10.5 SDKs without problem, for 10.6 compilation works (unlike g++-4.2), but linking fails, since on Snow Leopard, system libraries are only 3-way: i386 x86_64 ppc, i.e. ppc64 is missing:</div>
<div><div>g++-4.0 -mmacosx-version-min=10.6 -isysroot /Developer/SDKs/MacOSX10.6.sdk/ -arch ppc64 test.cpp -o test</div><div>ld: warning: in /Developer/SDKs/MacOSX10.6.sdk//usr/lib/crt1.10.5.o, missing required architecture ppc64 in file</div>
<div>ld: warning: in /Developer/SDKs/MacOSX10.6.sdk//usr/lib/powerpc-apple-darwin10/4.0.1/libstdc++.dylib, missing required architecture ppc64 in file</div><div>ld: warning: in /Developer/SDKs/MacOSX10.6.sdk//usr/lib/libgcc_s.10.5.dylib, missing required architecture ppc64 in file</div>
<div>ld: warning: in /Developer/SDKs/MacOSX10.6.sdk//usr/lib/libSystemStubs.a, missing required architecture ppc64 in file</div><div>ld: warning: in /Developer/SDKs/MacOSX10.6.sdk//usr/lib/libSystem.dylib, missing required architecture ppc64 in file</div>
<div>Undefined symbols:</div><div>  &quot;_fdopen&quot;, referenced from:</div><div>      _main in cckrrB6h.o</div><div>  &quot;std::ios_base::Init::Init()&quot;, referenced from:</div><div>      __static_initialization_and_destruction_0(int, int)in cckrrB6h.o</div>
<div>  &quot;___gxx_personality_v0&quot;, referenced from:</div><div>      ___gxx_personality_v0$non_lazy_ptr in cckrrB6h.o</div><div>  &quot;std::ios_base::Init::~Init()&quot;, referenced from:</div><div>      ___tcf_0 in cckrrB6h.o</div>
<div>  &quot;___cxa_atexit&quot;, referenced from:</div><div>      __static_initialization_and_destruction_0(int, int)in cckrrB6h.o</div><div>  &quot;_fwrite&quot;, referenced from:</div><div>      _main in cckrrB6h.o</div>
<div>ld: symbol(s) not found</div><div>collect2: ld returned 1 exit status</div><div><br></div><div>So to sum-up: Apple&#39;s developer tools contain only one g++-4.0 binary and only one g++-4.2. They also contain one SDK for each Mac OS X version for which it supports cross-compiling. These SDKs each contain system header files, system libraries, and gcc&#39;s internal headers (C++ standard library headers). The single g++-4.x binary uses, based on the SDK selected with -isysroot (macosx-version in boost.build), for linking different libraries and object files and for compiling different internal (and system) headers. Successful compilation with -arch ppc64 depends both on which g++ version you use (4.0 or 4.2) and which OS version you are (cross-)compiling for:</div>
<div><br></div><div>g++-4.2:</div><div>10.4 SDK: does not work for any arch (gcc 4.2 simply was not available in Tiger, C++ internal headers for 4.2 missing)</div><div>10.5 SDK: all archs work</div><div>10.6 SDK: -arch ppc64 does not work (Snow Leopard does not support running ppc64 executables (&quot;Bad CPU type in executable&quot;), it does support running ppc executables via Rosetta; and on Snow Leopard, system libraries are only 3-way: i386 x86_64 ppc;  ppc64 is missing)</div>
<div><br></div><div>g++-4.0:</div><div>10.4 SDK: all archs work (but beware that not all system libraries are 4-way, some are only 2-way (32-bit) - see paragraph below)</div><div>10.5 SDK: all archs work</div><div>10.6 SDK: same as g++-4.2 wth 10.6 SDK, just does not fail on compiling (internal headers for ppc64 are not there so I don&#39;t understand this), but rather on linking (ppc64 internal object files and system libraries do not exist)</div>
<div><br></div><div>The only other thing to be aware of is that &quot;g++&quot; defaults to &quot;g++-4.0&quot; when building on Tiger and Leopard, and to &quot;g++-4.2&quot; when building on Snow Leopard.</div><div><br></div>
<div>So e.g. if you use g++-4.0 or g++-4.2 and compile for 10.5 SDK, you can get 4-way binaries running on 10.5 and later. If you use g++-4.0 and compile for 10.4 SDK, you can get 4-way binaries running on 10.4 or later, but be vary that on Tiger, e.g. system&#39;s libz is 4-way, but system&#39;s libbz2 is only 2-way (32-bit), so you have to supply your own 4-way bz2 to iostreams (only a few libraries on Tiger were 4-way). And if you do that with your own 4-way static build of libbz2, you run into boost.build&#39;s library path issue that I won&#39;t go into here (this post is already way longer than I intendet it to be).</div>
<div><br></div></div></div><div>Sorry for the huge post, but I hope this attempt makes things a little bit more understandable w.r.t. building for ppc64 (and even others) _on_ Snow Leopard _for_ various target versions of Mac OS X. </div>
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