zmk.Toolchain - Man Page

module providing information and configuration about compiler toolchain

Synopsis

include z.mk

$(eval $(call ZMK.Import,Toolchain))

Description

The Toolchain module encapsulates information about the used C and C++ compilers. This knowledge is mainly consumed internally by other modules and templates, but can be used directly to construct custom rules.

Targets

This module does not provide any targets.

Variables

This module provides the following variables.

Please take note that make supports target-specific variables, where a specific variable, for example Cflags or Ldlibs takes a particular value only while building a specific target as well as all the targets that it depends on. This scheme is removes the need for additional variables manually customized to a specific target.

CC

The C compiler.

CPP

The pre-processor, responsible for macros and include directives.

CXX

The C++ compiler.

Cflags

Configuration options for the C compiler.

This variable should be used to pass options such as -Wall, -O2, or -fpic. Please refer to your compiler manual for details.

This variable is often abused, mainly for simplicity, as a kitchen-sink that holds all of the compiler and linker options. This is discouraged.

Cppflags

Configurations options for the pre-processor.

This variable should be used to provide command line options that alter the include search path, such as -I, or define a pre-processor macro, such as -D.

Cxxflags

Configuration options for the C++ compiler. This variable the equivalent of Cflags for the C++ compiler.

Objcflags

Configuration options for the Objective C compiler. This variable the equivalent of Cflags for the Objective C compiler.

Arflags

Configuration options for the ar program.

Target_arch

Compiler options for performing architecture selection.

This variable is not used by zmk. Cross compilation is supported by selecting a cross-compiling CC or CXX.

Ldlibs

Additional libraries to link with.

Libraries are provided in the form -lfoo where foo is the name of the library, without the prefix lib. Given the choice of static and dynamic libraries, the linker will prefer dynamic linking. You can a specific library statically with the following option sequence. -Wl,-dn -lfoo -Wl,-dy. The first segment -Wl,-dn turns off dynamic linking -lfoo links to the library libfoo.a while the final -Wl,-dy turns dynamic linking back again. Note that using this sequence the final executable is not entirely statically linked. If libfoo.a has any additional dependences those must be linked as well, either dynamically or statically.

Ldflags

Configuration options for the linker.

This variable should be used to provide command line options that alter the linker search path, such as -L, or customize linker behavior. Note that the linker is not invoked directly, but through the compiler front-end. For example, when using gcc, one would typically pass -Wl,foo in order to pass the option foo to the linker.

exe

The suffix for executables. It is either empty or has the value .exe, if the image format of the resulting executable is either PE or MZ.

This variable is automatically used by zmk when building executables.

Toolchain.SysRoot

Path of the root directory where the compiler looks for headers and libraries. A non-empty value causes --sysroot=$(Toolchain.SysRoot) to be passed to the compiler whenever it is used for compiling, linking or pre-processing.

The default value is $(Configure.SysRoot), namely the preference from the configuration system.

Toolchain.DependencyTracking

Expands to yes, if compilation of C, C++ and Objective C source files will automatically generate dependency rules for Make.

The default value is $(Configure.DependencyTracking), namely the preference from the configuration system.

Toolchain.ImageFormat

Identifier or the application image format generated by both the C compiler or the C++ compiler. If the two compilers produce different image formats, for example because one is a cross-compiler the effective value is Mixed.

Toolchain.IsCross

Expands to yes if programs created by either the C compiler or the C++ compiler cannot be executed on the machine performing the build.

Toolchain.IsGcc

Expands to yes, if both the C and C++ compilers are from the GNU Compiler Collection.

Toolchain.IsClang

Expands to yes, if both the C and C++ compilers are from the clang project.

Toolchain.IsWatcom

Expands to yes, if both the C and C++ compilers are from the Open Watcom compiler.

Toolchain.CC.IsAvaiable

Expands to yes if the C compiler is available.

Toolchain.CC.ImageFormat

Identifier or the application image format generated by the C compiler. Refer to the documentation of OS.ImageFormat for a description of known formats.

Unless cross-compiling, the default value is $(OS.ImageFormat).

Toolchain.CC.IsCross

Expands to yes if programs created by the C compiler cannot be executed on the machine performing the build.

Toolchain.CC.IsGcc

Expands to yes, if the selected C compiler is the GNU Compiler Collection. This variable, as well as several others documented below, can be used to conditionally enable compiler specific options in a manner that does not break when another compiler is used.

Toolchain.CC.IsClang

Expands to yes, if the selected C compiler is clang.

Toolchain.CC.IsWatcom

Expands to yes, if the selected C compiler is the Open Watcom compiler.

Toolchain.CC.IsTcc

Expands to yes, if the selected C compiler is the Tiny C Compiler.

Toolchain.CXX.IsAvaiable

Expands to yes if the C++ compiler is available.

Toolchain.CXX.ImageFormat

Identifier or the application image format generated by the C++ compiler.

Unless cross-compiling, the default value is $(OS.ImageFormat).

Toolchain.CXX.IsCross

Expands to yes if programs created by the C++ compiler cannot be executed on the machine performing the build.

Toolchain.CXX.IsGcc

Expands to yes, if the selected C++ compiler is the GNU Compiler Collection.

Toolchain.CXX.IsClang

Expands to yes, if the selected C++ compiler is clang.

Toolchain.CXX.IsWatcom

Expands to yes, if the selected C++ compiler is the Open Watcom compiler.

Examples

History

The Toolchain module first appeared in zmk 0.3

Authors

Zygmunt Krynicki <me@zygoon.pl>

Info

May 3, 2020