c - CMake cross-compile with specific linker doesn't pass arguments to armlink

Question

I am trying to cross-compile a project for embedded ARM Cortex builds, but I am unable to get the linker working. I want to use armlink, but no files are passed to armlink and hence no .elf file is produced.

My CMakeLists.txt is pretty simple and given below. The failure is shown after that which shows that armlink was invoked by the makefile without any arguments.

Any pointers will help - I searched and read many posts, but they all seem to have more involved requirements.

cmake_minimum_required(VERSION 2.8)

project(test_arm)
enable_language(C ASM)

# Cross-compilation for ARM
SET(CMAKE_C_COMPILER armcc)
SET(CMAKE_LINKER armlink)
SET(CMAKE_C_LINK_EXECUTABLE armlink)

SET(CMAKE_C_FLAGS "--cpu=Cortex-M3")
SET(LINK_FLAGS "--map --ro-base=0x0 --rw-base=0x0008000 --first='boot.o(RESET)' --datacompressor=off")
SET(CMAKE_EXE_LINKER_FLAGS "--map --ro-base=0x0 --rw-base=0x0008000 --first='boot.o(RESET)' --datacompressor=off")

include_directories(../include)

add_executable(blinky blinky.c)
set_target_properties(blinky PROPERTIES LINKER_LANGUAGE C)

The failure is as follows, but I guess it would be obvious to someone given that I have some stupid issue in my CMakeLists:

$ make VERBOSE=1
[100%] Building C object CMakeFiles/blinky.dir/blinky.c.o
/usr/bin/cmake -E cmake_link_script CMakeFiles/blinky.dir/link.txt --verbose=1
armlink
Linking C executable blinky
Product: DS-5 Professional 5.21.0 [5210017]
Component: ARM Compiler 5.05 update 1 (build 106)
Tool: armlink [4d0efa]
For support see http://www.arm.com/support/
Software supplied by: ARM Limited
Usage: armlink option-list input-file-list
where
....

I was expecting the CMake generated Makefile to invoke armlink with something like:

armlink --map --ro-base=0x0 --rw-base=0x0008000 
  --first='boot.o(RESET)' --datacompressor=off 
  CMakeFiles/blinky.dir/blinky.c.o -o blinky.elf

Answer 1

Starting with CMake v3.5 you don't need a toolchain anymore for Keil ARM C/C++ compilation tools:

Support was added for the ARM Compiler (arm.com) with compiler id ARMCC.

Just set your C/CXX compiler variables accordingly

cmake -DCMAKE_C_COMPILER:PATH="C:Program Files (x86)DS-5inarmcc.exe"
      -DCMAKE_CXX_COMPILER:PATH="C:Program Files (x86)DS-5inarmcc.exe"
      ...

References

• ARMCC toolchain support
• Add support for the ARM Compiler (arm.com)
• CMake Error at CMakeLists.txt:30 (project): No CMAKE_C_COMPILER could be found