Re: More about cross compiling
Re: More about cross compiling
- Subject: Re: More about cross compiling
- From: Philipp Donzé <email@hidden>
- Date: Wed, 27 Oct 2004 20:37:26 +0200
As far as I know, this is no magic command-line switch that can be
passed to
gcc to have it generate code targetting a different CPU.
From the gcc man page:
-b machine
The argument machine specifies the target machine for
compilation.
I've also fiddled with this, some time ago.
But I wasn't able to tell XCode to use this argument correctly.
It is important that the target options ("-b" and "-V") are set before
any other options. I.e. before the "-x" argument.
Here is what XCode executes when building a standard tool:
--------------------
CompileC build/Test.build/Test.build/Objects-normal/ppc/main.o main.c
normal ppc c com.apple.compilers.gcc.3_3
cd /Test
/usr/bin/gcc-3.3 -x c -arch ppc -pipe -Wno-trigraphs -fasm-blocks
-fpascal-strings -Os -mtune=G4 -fmessage-length=0 -F/Test/build
-I/Test/build/include
-I/Test/build/Test.build/Test.build/DerivedSources
-Wp,-header-mapfile,/Test/build/Test.build/Test.build/Test.hmap -c
/Test/main.c -o
/Test/build/Test.build/Test.build/Objects-normal/ppc/main.o
Ld /Test/build/Test
cd /Test
/usr/bin/gcc-3.3 -o /Test/build/Test -L/Test/build -F/Test/build
-filelist
/Test/build/Test.build/Test.build/Objects-normal/Test.LinkFileList
-arch ppc -prebind -Wl,-no_arch_warnings
--------------------
If you set the target options using the "Other C Flags" in the build
settings (here "-b m68k-atari-mint -V 3.3.3"), you encounter the
following problem:
--------------------
CompileC build/Test.build/Test.build/Objects-normal/ppc/main.o main.c
normal ppc c com.apple.compilers.gcc.3_3
cd /Test
/usr/bin/gcc-3.3 -x c -arch ppc -pipe -Wno-trigraphs -fasm-blocks
-fpascal-strings -Os -mtune=G4 -fmessage-length=0 -F/Test/build
-I/Test/build/include
-I/Test/build/Test.build/Test.build/DerivedSources
-Wp,-header-mapfile,/Test/build/Test.build/Test.build/Test.hmap -b
m68k-atari-mint -V 3.3.3 -c /Test/main.c -o
/Test/build/Test.build/Test.build/Objects-normal/ppc/main.o
gcc-3.3: `-b' must come at the start of the command line
--------------------
So the "Other C Flags" is no solution for our problem, as they are
added after the "-x c" flag.
And if you've found a solution for the problem above, you'll have to
solve the next problem:
"Not Apple-GCC" (=GCC from Free Software Foundation) does not
understand many of the apple specific parameters. E.g. "-arch ppc"
"-fpascal-strings" "-mtune=G4"... So you'll have get XCode to a point
where it doesn't add these parameters to the command line.
Probably you'll try to resolve this by defining your own compiler
specification "gcc.pbcompspec". (That's what I tried to do.)
After lots of crashes, you'll perhaps get to a point where it calls
your cross-compiler with the correct arguments.
Being happy about your success, you'll try to create a cross-compiler
project with more than a simple "Hello World" program.
There I encountered the next problem: When building, Xcode calls
correctly your compiler for the first file. But after that it calls
again Apples own GCC (for compiling or linking, I don't remember
exactly). => no success.
That's where I stopped my effort in making Xcode the universal
cross-compiling tool. I even trashed my compiler specification...
Stupid, he?
With Xcode Apple has created a nice development tool. It would be great
if they added cross-compiler support (e.g. support for FSF GCC). This
would make Mac OS X a great platform for developing for any target
platform (e.g. embedded systems)!
Philipp
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