Re: [EXT] Re: Building "Fat" Mac Binary, or Cross-Compiling from ARM arch to x86-64

FWIW, I’m working a lot with Macs, both Intel-based and Apple Silicon-based. 

In my experience, it’s been never useful to build “fat” binaries. They brought nothing but problems. 

In our place we build x86_64 binaries for Intel, and AARCH64 for Silicon - and is been perfectly satisfactory here. I recommend considering the same (proven) approach. 

P.S. Can’t comment on cross-compiling - haven’t done that - but would imagine it should be reasonably straightforward. 
—
Regards,
Uri

Secure Resilient Systems and Technologies
MIT Lincoln Laboratory

> On Jan 2, 2025, at 19:17, 'Mounir IDRASSI' via openssl-users <[email protected]> wrote:
> 
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> 
>> On 1/2/2025 10:59 PM, Viktor Dukhovni wrote:
>> Unfortunately, that can't trivially work for OpenSSL, because
>> architecture-specific assembly targets are included in the build.  You'd
>> need to build *both* the ARM *and* X86_64 assembly targets, invoking the
>> appropriate assembler on each one, and producing either object code for
>> that particular platform for inclusion in the "fat" binary, or somehow
>> producting a "fat" objec that is "empty" for one of the targets.
>> 
>> How to do that, requires more detailed knowledge of fat binaries than I
>> can muster.
> 
> To create a fat binary on macOS, you need to use lipo command to combine both x64 and arm64 libraries that must be built separately as Viktor explained:
> lipo -create -output libcrypto.dylib libcrypto.dylib.x64 libcrypto.dylib.arm64
> 
> We have a script that automates this process. It fetches the OpenSSL tarball from GitHub, performs separate x64 and arm64 builds, invokes lipo, updates the install_name and handles code signing. The script is too long to include here so I’ve shared it as a GitHub gist:
> 
> https://gist.github.com/idrassi/cf4ef1a81f9bb5b7d7b3e8382b942665
> 
> Take a look at the function lipo_dylib that calls lipo:
> 
> -----------------------------------------------------------------
> 
> lipo_dylib() {
>     local lib_name="\$1"
>     local src_x86_64="${INSTALL_PREFIX_X86_64}/lib/${lib_name}"
>     local src_arm64="${INSTALL_PREFIX_ARM64}/lib/${lib_name}"
>     local dest="${INSTALL_PREFIX_UNIVERSAL}/lib/${lib_name}"
> 
>     if [[ -f "${src_x86_64}" && -f "${src_arm64}" ]]; then
>         echo "Creating universal binary for ${lib_name}..."
>         lipo -create -output "${dest}" "${src_x86_64}" "${src_arm64}"
> 
>         # Use install_name_tool to set the correct install_name
>         echo "Updating install_name for ${lib_name}..."
>         install_name_tool -id "${INSTALL_PATH}/lib/${lib_name}" "${dest}" || {
>             echo "Failed to update install_name for ${lib_name}"
>             exit 1
>         }
> 
>         # If libssl depends on libcrypto, update the dependency path
>         if [[ "${lib_name}" == "libssl.3.dylib" ]]; then
>             echo "Updating dependency of libssl.3.dylib to point to ${INSTALL_PATH}/lib/libcrypto.3.dylib..."
>             install_name_tool -change "/tmp/openssl_x86_64/lib/libcrypto.3.dylib" "${INSTALL_PATH}/lib/libcrypto.3.dylib" "${dest}" || {
>                 echo "Failed to update libssl.3.dylib dependency for x86_64"
>                 exit 1
>             }
>             install_name_tool -change "/tmp/openssl_arm64/lib/libcrypto.3.dylib" "${INSTALL_PATH}/lib/libcrypto.3.dylib" "${dest}" || {
>                 echo "Failed to update libssl.3.dylib dependency for arm64"
>                 exit 1
>             }
>         fi
>     else
>         echo "Error: Missing ${lib_name} for one or both architectures."
>         exit 1
>     fi
> }
> --------------------
> 
> Mounir IDRASSI
> 
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