Re: Cross compiling for iOS

[Russell Keith-Magee <russell@keith-magee.com>]

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I can’t speak to any of the eccentricities introduced by using OSX Cross, but the build process for iOS isn’t quite the same as it is for the platforms - it requires some pre- and post- processing. You don't just invoke ./configure from the command line as you would for a “normal” autoconf project.

There’s a `generate_darwin_source_and_headers.py` script in the root of the libffi code checkout; when you execute that, it generates `build_` folders for each architecture, and runs configure for you. 

You can see these tools in action in the repo I maintain for libFFI support on iOS/tvOS/watchOS; here’s the invocation of the helper script:
https://github.com/beeware/cpython-apple-source-deps/blob/main/Makefile#L474

And the build itself:
https://github.com/beeware/cpython-apple-source-deps/blob/main/Makefile#L339 

Each pass will give you a binary for a *single* ABI and architecture; Depending on your intended usage, you may need to combine them into  “fat” binaries for each ABI; depending on how you’re using the library, you may also need to combine the multiple ABI fat binaries into a single XCframework.

Or - the releases page for the repo I just linked has pre-built (single ABI and architecture) binaries.

https://github.com/beeware/cpython-apple-source-deps/releases/tag/libFFI-3.4.4-1

Hope that helps,
Russ Magee %-)

On 1 February 2024 at 3:04:54 pm, saleem gagguturu via Libffi-discuss (libffi-discuss@sourceware.org) wrote:

Hi,  

I'm trying to cross-compile libffi for iOS from Debian. I managed to cross-compile it successfully for MacOS (arm64 and x86) using OSX Cross but I'm getting some errors for iOS.  

My configure command is:  

./configure --host=arm-apple-darwin11 --prefix=$IOS_TOOLCHAIN_ROOT --libdir=$IOS_TOOLCHAIN_ROOT/lib --disable-docs  

This is the error I'm getting:  


libtool: link: ( cd ".libs" && rm -f "libffi_convenience.la" && ln -s "../libffi_convenience.la" "libffi_convenience.la" )  
Undefined symbols for architecture arm64:  
"_ffi_call", referenced from:  
_ffi_raw_call in raw_api.o  
_ffi_java_raw_call in java_raw_api.o  
"_ffi_closure_trampoline_table_page", referenced from:  
_ffi_closure_alloc in closures.o  
"_ffi_prep_cif_machdep", referenced from:  
_ffi_prep_cif_core in prep_cif.o  
"_ffi_prep_cif_machdep_var", referenced from:  
_ffi_prep_cif_core in prep_cif.o  
"_ffi_prep_closure_loc", referenced from:  
_ffi_prep_closure in prep_cif.o  
_ffi_prep_raw_closure_loc in raw_api.o  
_ffi_prep_raw_closure in raw_api.o  
_ffi_prep_java_raw_closure_loc in java_raw_api.o  
_ffi_prep_java_raw_closure in java_raw_api.o  
ld: symbol(s) not found for architecture arm64  

I've raised an issue with full logs here https://github.com/libffi/libffi/issues/821  

Anyone know any workaround for this? I need libffi as it's a dependency to Glib.  

Thanks