many `unrecognized opcode` errors when cross compiling for ppc64le

[ReenigneArcher]

When cross-compiling for ppc64le from x86_64 Ubuntu I get the following errors.

[  0%] Building CXX object _deps/boost-build/libs/atomic/CMakeFiles/boost_atomic.dir/src/lock_pool.cpp.o
[  0%] Building CXX object _deps/boost-build/libs/chrono/CMakeFiles/boost_chrono.dir/src/chrono.cpp.o
[  0%] Building C object _deps/boost-build/libs/container/CMakeFiles/boost_container.dir/src/alloc_lib.c.o
[  0%] Building ASM object _deps/boost-build/libs/context/CMakeFiles/boost_context.dir/src/asm/make_x86_64_sysv_elf_gas.S.o
make_x86_64_sysv_elf_gas.S: Assembler messages:
make_x86_64_sysv_elf_gas.S:59: Error: unrecognized opcode: `movq'
make_x86_64_sysv_elf_gas.S:62: Error: unrecognized opcode: `andq'
make_x86_64_sysv_elf_gas.S:66: Error: unrecognized opcode: `leaq'
make_x86_64_sysv_elf_gas.S:70: Error: unrecognized opcode: `movq'
make_x86_64_sysv_elf_gas.S:73: Error: unrecognized opcode: `stmxcsr'
make_x86_64_sysv_elf_gas.S:75: Error: unrecognized opcode: `fnstcw'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:84: Error: unrecognized opcode: `leaq'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:87: Error: unrecognized opcode: `movq'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:90: Error: unrecognized opcode: `leaq'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:93: Error: unrecognized opcode: `movq'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:133: Error: unrecognized opcode: `ret'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:146: Error: unrecognized opcode: `push'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:149: Error: unrecognized opcode: `jmp'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:154: Error: unrecognized opcode: `xorq'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:156: Error: unrecognized opcode: `call'
/home/runner/work/build-deps/build-deps/build/_deps/boost-src/libs/context/src/asm/make_x86_64_sysv_elf_gas.S:157: Error: unrecognized opcode: `hlt'
make[2]: *** [_deps/boost-build/libs/context/CMakeFiles/boost_context.dir/build.make:78: _deps/boost-build/libs/context/CMakeFiles/boost_context.dir/src/asm/make_x86_64_sysv_elf_gas.S.o] Error 1
make[2]: Leaving directory '/home/runner/work/build-deps/build-deps/build'
make[1]: *** [CMakeFiles/Makefile2:2041: _deps/boost-build/libs/context/CMakeFiles/boost_context.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

https://github.com/LizardByte/build-deps/actions/runs/16693866779/job/47255227124?pr=476#step:15:36

I should add that this is with boost 1.87.0, as we're stuck with this version until the codebase is updated to support code that was removed in 1.88+. If this has already been fixed, I apologize.

[mbs-c]

I can confirm that all cmake builds for power are affected. This has nothing to do with cross-compilation, as I can reproduce the issue on a Power machine with both Linux and AIX. The CMAKE_SYSTEM_PROCESSOR values powerpc (AIX) and ppc64le (Linux on Power) are simply not handled in CMakeLists.txt.

[mbs-c]

Quick and dirty workaround for Linux on Power:

if (CMAKE_SYSTEM_PROCESSOR STREQUAL "ppc64le") # Linux on Power
  set(BOOST_CONTEXT_ARCHITECTURE "ppc64")
endif ()

[ReenigneArcher]

Confirming that worked for me as well. Thank you!

[mbs-c]

I'm still struggling with AIX, though. The following should work (assuming OBJECT_MODE=64):

if (CMAKE_SYSTEM_PROCESSOR STREQUAL "powerpc")
  set(BOOST_CONTEXT_ARCHITECTURE "ppc64")
  set(BOOST_CONTEXT_BINARY_FORMAT "xcoff")
endif ()

I'm getting strange "undefined symbol" errors from the assembler, though:

   "/usr/bin/as" -a64 -many -o CMakeFiles/boost_context.dir/src/asm/make_ppc64_sysv_xcoff_gas.S.o CMakeFiles/boost_context.dir/src/asm/make_ppc64_sysv_xcoff_gas.s
  Assembler:
  CMakeFiles/boost_context.dir/src/asm/make_ppc64_sysv_xcoff_gas.s: line 13: undefined symbol ".make_fcontext"
  CMakeFiles/boost_context.dir/src/asm/make_ppc64_sysv_xcoff_gas.s: line 72: undefined symbol "._exit"
  .ibm-clang: error: assembler command failed with exit code 1 (use -v to see invocation)

   "/usr/bin/as" -a64 -many -o CMakeFiles/boost_context.dir/src/asm/ontop_ppc64_sysv_xcoff_gas.S.o CMakeFiles/boost_context.dir/src/asm/ontop_ppc64_sysv_xcoff_gas.s
  Assembler:
  CMakeFiles/boost_context.dir/src/asm/ontop_ppc64_sysv_xcoff_gas.s: line 13: undefined symbol ".ontop_fcontext"
  .ibm-clang: error: assembler command failed with exit code 1 (use -v to see invocation)

   "/usr/bin/as" -a64 -many -o CMakeFiles/boost_context.dir/src/asm/jump_ppc64_sysv_xcoff_gas.S.o CMakeFiles/boost_context.dir/src/asm/jump_ppc64_sysv_xcoff_gas.s
  Assembler:
  CMakeFiles/boost_context.dir/src/asm/jump_ppc64_sysv_xcoff_gas.s: line 13: undefined symbol ".jump_fcontext"
  .ibm-clang: error: assembler command failed with exit code 1 (use -v to see invocation)