# cmake_host_system_information

Query various host system information.

## Synopsis

    Query host system specific information
      cmake_host_system_information(RESULT <variable> QUERY <key> ...)

    Query Windows registry
      cmake_host_system_information(RESULT <variable> QUERY WINDOWS_REGISTRY <key> ...)

## Query host system specific information

    cmake_host_system_information(RESULT <variable> QUERY <key> ...)

Queries system information of the host system on which cmake runs. One or more `<key>` can be provided to select the information to be queried. The list of queried values is stored in `<variable>`.

`<key>` can be one of the following values:

`NUMBER_OF_LOGICAL_CORES`

  Number of logical cores

`NUMBER_OF_PHYSICAL_CORES`

  Number of physical cores

`HOSTNAME`

  Hostname

`FQDN`

  Fully qualified domain name

`TOTAL_VIRTUAL_MEMORY`

  Total virtual memory in MiB [1]

`AVAILABLE_VIRTUAL_MEMORY`

  Available virtual memory in MiB [1]

`TOTAL_PHYSICAL_MEMORY`

  Total physical memory in MiB [1]

`AVAILABLE_PHYSICAL_MEMORY`

  Available physical memory in MiB [1]

`IS_64BIT`

  Added in version 3.10.

  One if processor is 64Bit

`HAS_FPU`

  Added in version 3.10.

  One if processor has floating point unit

`HAS_MMX`

  Added in version 3.10.

  One if processor supports MMX instructions

`HAS_MMX_PLUS`

  Added in version 3.10.

  One if processor supports Ext. MMX instructions

`HAS_SSE`

  Added in version 3.10.

  One if processor supports SSE instructions

`HAS_SSE2`

  Added in version 3.10.

  One if processor supports SSE2 instructions

`HAS_SSE_FP`

  Added in version 3.10.

  One if processor supports SSE FP instructions

`HAS_SSE_MMX`

  Added in version 3.10.

  One if processor supports SSE MMX instructions

`HAS_AMD_3DNOW`

  Added in version 3.10.

  One if processor supports 3DNow instructions

`HAS_AMD_3DNOW_PLUS`

  Added in version 3.10.

  One if processor supports 3DNow+ instructions

`HAS_IA64`

  Added in version 3.10.

  One if IA64 processor emulating x86

`HAS_SERIAL_NUMBER`

  Added in version 3.10.

  One if processor has serial number

`PROCESSOR_SERIAL_NUMBER`

  Added in version 3.10.

  Processor serial number

`PROCESSOR_NAME`

  Added in version 3.10.

  Human readable processor name

`PROCESSOR_DESCRIPTION`

  Added in version 3.10.

  Human readable full processor description

`OS_NAME`

  Added in version 3.10.

  The host operating system name:

  - On UNIX platforms, this is `uname -s`.

  - On Apple platforms, this is `sw_vers -productName`.

  - On Windows, this is `Windows`.

  See also `CMAKE_HOST_SYSTEM_NAME`.

`OS_RELEASE`

  Added in version 3.10.

  The OS sub-type e.g. on Windows `Professional`

`OS_VERSION`

  Added in version 3.10.

  The OS build ID

`OS_PLATFORM`

  Added in version 3.10.

  See `CMAKE_HOST_SYSTEM_PROCESSOR`

`MSYSTEM_PREFIX`

  Added in version 3.28.

  Available only on Windows hosts. In a MSYS or MinGW development environment that sets the `MSYSTEM` environment variable, this is its installation prefix. Otherwise, this is the empty string.

`DISTRIB_INFO`

  Added in version 3.22.

  Read `/etc/os-release` file and define the given `<variable>` into a list of read variables

`DISTRIB_<name>`

  Added in version 3.22.

  Get the `<name>` variable (see man 5 os-release) if it exists in the `/etc/os-release` file

  Example:

      cmake_host_system_information(RESULT PRETTY_NAME QUERY DISTRIB_PRETTY_NAME)
      message(STATUS "${PRETTY_NAME}")

      cmake_host_system_information(RESULT DISTRO QUERY DISTRIB_INFO)

      foreach(VAR IN LISTS DISTRO)
        message(STATUS "${VAR}=`${${VAR}}`")
      endforeach()

  Output:

      -- Ubuntu 20.04.2 LTS
      -- DISTRO_BUG_REPORT_URL=`https://bugs.launchpad.net/ubuntu/`
      -- DISTRO_HOME_URL=`https://www.ubuntu.com/`
      -- DISTRO_ID=`ubuntu`
      -- DISTRO_ID_LIKE=`debian`
      -- DISTRO_NAME=`Ubuntu`
      -- DISTRO_PRETTY_NAME=`Ubuntu 20.04.2 LTS`
      -- DISTRO_PRIVACY_POLICY_URL=`https://www.ubuntu.com/legal/terms-and-policies/privacy-policy`
      -- DISTRO_SUPPORT_URL=`https://help.ubuntu.com/`
      -- DISTRO_UBUNTU_CODENAME=`focal`
      -- DISTRO_VERSION=`20.04.2 LTS (Focal Fossa)`
      -- DISTRO_VERSION_CODENAME=`focal`
      -- DISTRO_VERSION_ID=`20.04`

If `/etc/os-release` file is not found, the command tries to gather OS identification via fallback scripts. The fallback script can use various distribution-specific files to collect OS identification data and map it into man 5 os-release variables.

### Fallback Interface Variables

CMAKE_GET_OS_RELEASE_FALLBACK_SCRIPTS

  In addition to the scripts shipped with CMake, a user may append full paths of their script(s) to this list. The script filename has the following format: `NNN-<name>.cmake`, where `NNN` is three digits used to apply collected scripts in a specific order.

CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_<varname>

  Variables collected by the user provided fallback script ought to be assigned to CMake variables using this naming convention. Example, the `ID` variable from the manual becomes `CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID`.

CMAKE_GET_OS_RELEASE_FALLBACK_RESULT

  The fallback script ought to store names of all assigned `CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_<varname>` variables in this list.

Example:

    # 000-FallbackScript.cmake
    #
    # Try to detect some old distribution
    # See also
    # - http://linuxmafia.com/faq/Admin/release-files.html
    #
    if(NOT EXISTS "${CMAKE_SYSROOT}/etc/foobar-release")
      return()
    endif()
    # Get the first string only
    file(
        STRINGS "${CMAKE_SYSROOT}/etc/foobar-release" CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT
        LIMIT_COUNT 1
      )
    #
    # Example:
    #
    #   Foobar distribution release 1.2.3 (server)
    #
    if(CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT MATCHES "Foobar distribution release ([0-9\.]+) .*")
      set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_NAME Foobar)
      set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_PRETTY_NAME "${CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT}")
      set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID foobar)
      set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION ${CMAKE_MATCH_1})
      set(CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION_ID ${CMAKE_MATCH_1})
      list(
          APPEND CMAKE_GET_OS_RELEASE_FALLBACK_RESULT
          CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_NAME
          CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_PRETTY_NAME
          CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_ID
          CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION
          CMAKE_GET_OS_RELEASE_FALLBACK_RESULT_VERSION_ID
        )
    endif()
    unset(CMAKE_GET_OS_RELEASE_FALLBACK_CONTENT)

Then this script can be applied as a fallback to determine the missing host system information:

    list(
      APPEND
      CMAKE_GET_OS_RELEASE_FALLBACK_SCRIPTS
      ${CMAKE_CURRENT_SOURCE_DIR}/000-FallbackScript.cmake
    )

    cmake_host_system_information(RESULT info QUERY DISTRIB_INFO)

Footnotes

[1] (1,2,3,4)

One MiB (mebibyte) is equal to 1024x1024 bytes.

## Query Windows registry

Added in version 3.24.

    cmake_host_system_information(RESULT <variable>
                                  QUERY WINDOWS_REGISTRY <key> [VALUE_NAMES|SUBKEYS|VALUE <name>]
                                  [VIEW (64|32|64_32|32_64|HOST|TARGET|BOTH)]
                                  [SEPARATOR <separator>]
                                  [ERROR_VARIABLE <result>])

Performs query operations on local computer registry subkey. Returns a list of subkeys or value names that are located under the specified subkey in the registry or the data of the specified value name. The result of the queried entity is stored in `<variable>`.

Note

Querying registry for any other platforms than `Windows`, including `CYGWIN`, will always returns an empty string and sets an error message in the variable specified with sub-option `ERROR_VARIABLE`.

`<key>` specify the full path of a subkey on the local computer. The `<key>` must include a valid root key. Valid root keys for the local computer are:

- `HKLM` or `HKEY_LOCAL_MACHINE`

- `HKCU` or `HKEY_CURRENT_USER`

- `HKCR` or `HKEY_CLASSES_ROOT`

- `HKU` or `HKEY_USERS`

- `HKCC` or `HKEY_CURRENT_CONFIG`

And, optionally, the path to a subkey under the specified root key. The path separator can be the slash or the backslash. `<key>` is not case sensitive. For example:

    cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKLM")
    cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware")
    cmake_host_system_information(RESULT result QUERY WINDOWS_REGISTRY "HKCU\\SOFTWARE\\Kitware")

`VALUE_NAMES`

  Request the list of value names defined under `<key>`. If a default value is defined, it will be identified with the special name `(default)`.

`SUBKEYS`

  Request the list of subkeys defined under `<key>`.

`VALUE <name>`

  Request the data stored in value named `<name>`. If `VALUE` is not specified or argument is the special name `(default)`, the content of the default value, if any, will be returned.

      # query default value for HKLM/SOFTWARE/Kitware key
      cmake_host_system_information(RESULT result
                                    QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware")

      # query default value for HKLM/SOFTWARE/Kitware key using special value name
      cmake_host_system_information(RESULT result
                                    QUERY WINDOWS_REGISTRY "HKLM/SOFTWARE/Kitware"
                                    VALUE "(default)")

  Supported types are:

  - `REG_SZ`.

  - `REG_EXPAND_SZ`. The returned data is expanded.

  - `REG_MULTI_SZ`. The returned is expressed as a CMake list. See also `SEPARATOR` sub-option.

  - `REG_DWORD`.

  - `REG_QWORD`.

  For all other types, an empty string is returned.

`VIEW`

  Specify which registry views must be queried. When not specified, `BOTH` view is used.

  `64`

    Query the 64bit registry. On `32bit Windows`, returns always an empty string.

  `32`

    Query the 32bit registry.

  `64_32`

    For `VALUE` sub-option or default value, query the registry using view `64`, and if the request failed, query the registry using view `32`. For `VALUE_NAMES` and `SUBKEYS` sub-options, query both views (`64` and `32`) and merge the results (sorted and duplicates removed).

  `32_64`

    For `VALUE` sub-option or default value, query the registry using view `32`, and if the request failed, query the registry using view `64`. For `VALUE_NAMES` and `SUBKEYS` sub-options, query both views (`32` and `64`) and merge the results (sorted and duplicates removed).

  `HOST`

    Query the registry matching the architecture of the host: `64` on `64bit Windows` and `32` on `32bit Windows`.

  `TARGET`

    Query the registry matching the architecture specified by `CMAKE_SIZEOF_VOID_P` variable. If not defined, fallback to `HOST` view.

  `BOTH`

    Query both views (`32` and `64`). The order depends of the following rules: If `CMAKE_SIZEOF_VOID_P` variable is defined. Use the following view depending of the content of this variable:

    - `8`: `64_32`

    - `4`: `32_64`

    If `CMAKE_SIZEOF_VOID_P` variable is not defined, rely on architecture of the host:

    - `64bit`: `64_32`

    - `32bit`: `32`

`SEPARATOR`

  Specify the separator character for `REG_MULTI_SZ` type. When not specified, the character `\0` is used.

`ERROR_VARIABLE <result>`

  Returns any error raised during query operation. In case of success, the variable holds an empty string.