How to do it

We will use CMake to fill the definitions in config.h with sensible values for our platform and to compile our sample source file into an executable:

1. First, we define the minimum CMake version, project name, and project language:

cmake_minimum_required(VERSION 3.10 FATAL_ERROR)

project(recipe-05 CXX)

2. We then define the target executable, its source file, and include directories:

add_executable(processor-info "")

target_sources(processor-info
  PRIVATE
    processor-info.cpp
  )

target_include_directories(processor-info
  PRIVATE
    ${PROJECT_BINARY_DIR}
  )

3. We then go on to query the host system information for a number of keys:

foreach(key
  IN ITEMS
    NUMBER_OF_LOGICAL_CORES
    NUMBER_OF_PHYSICAL_CORES
    TOTAL_VIRTUAL_MEMORY
    AVAILABLE_VIRTUAL_MEMORY
    TOTAL_PHYSICAL_MEMORY
    AVAILABLE_PHYSICAL_MEMORY
    IS_64BIT
    HAS_FPU
    HAS_MMX
    HAS_MMX_PLUS
    HAS_SSE
    HAS_SSE2
    HAS_SSE_FP
    HAS_SSE_MMX
    HAS_AMD_3DNOW

    HAS_AMD_3DNOW_PLUS
    HAS_IA64
    OS_NAME
    OS_RELEASE
    OS_VERSION
    OS_PLATFORM
  )
  cmake_host_system_information(RESULT _${key} QUERY ${key})
endforeach()

4. Having defined the corresponding variables, we configure config.h:

configure_file(config.h.in config.h @ONLY)

5. Now we are ready to configure, build, and test the project:

$ mkdir -p build
$ cd build
$ cmake ..
$ cmake --build .
$ ./processor-info

Number of logical cores: 4
Number of physical cores: 2
Total virtual memory in megabytes: 15258
Available virtual memory in megabytes: 14678
Total physical memory in megabytes: 7858
Available physical memory in megabytes: 4072
Processor is 64Bit: 1
Processor has floating point unit: 1
Processor supports MMX instructions: 1
Processor supports Ext. MMX instructions: 0
Processor supports SSE instructions: 1
Processor supports SSE2 instructions: 1
Processor supports SSE FP instructions: 0
Processor supports SSE MMX instructions: 0
Processor supports 3DNow instructions: 0
Processor supports 3DNow+ instructions: 0
IA64 processor emulating x86 : 0
OS name: Linux
OS sub-type: 4.16.7-1-ARCH
OS build ID: #1 SMP PREEMPT Wed May 2 21:12:36 UTC 2018
OS platform: x86_64

6. The output will of course vary depending on the processor.