Meson Toolchain Files

Introduction to Meson Toolchain Files

Most applications that rely on the Meson build system have decent support for cross compilation, ie. compiling 32-bit binaries on a 64-bit system. It can be as easy as setting the CC, CXX, and PKG_CONFIG_PATH variables before using the meson setup .. command to compile 32-bit binaries on a 64-bit system. However, some projects are more complicated for many different reasons, leading to the necessity of Meson toolchain files. They specify compilers, options that should be invoked, the pkg-conf binary (or rather symlink that uses a certain personality file) to use, llvm-config to use, etc. This is required for Mesa's Nouveau and/or Swrast Vulkan drivers. It is also needed for Gstreamer (not in the book), which is a recommended dependency of Wine-9.14.

There are two Meson files: the cross toolchain file and the native toolchain file. There are different situations for using either.

Meson Toolchain File Dependencies

Required

Pkgconf Personalties (runtime)

mkdir -pv /usr/share/meson/cross

cat > /usr/share/meson/cross/lib32 << "EOF"
[binaries]
c = ['gcc', '-m32']
cpp = ['g++', '-m32']
rust = ['rustc', '--target', 'i686-unknown-linux-gnu']
pkg-config = 'i686-pc-linux-gnu-pkg-config'
ar = '/usr/bin/ar'
strip = '/usr/bin/strip'
cups-config = 'cups-config'
llvm-config = 'llvm-config'
exe_wrapper = ''

[properties]
sizeof_void* = 4
sizeof_long = 4

[host_machine]
system = 'linux'
subsystem = 'linux'
kernel = 'linux'
cpu_family = 'x86'
cpu = 'i686'
endian = 'little'
EOF

mkdir -pv /usr/share/meson/native

cat > /usr/share/meson/native/x86 << "EOF"
[binaries]
c = ['gcc', '-m32']
cpp = ['g++', '-m32']
rust = ['rustc', '--target', 'i686-unknown-linux-gnu']
pkg-config = 'i686-pc-linux-gnu-pkg-config'
ar = '/usr/bin/ar'
strip = '/usr/bin/strip'
cups-config = 'cups-config'
llvm-config = 'llvm-config'
exe_wrapper = ''

[properties]
sizeof_void* = 4
sizeof_long = 4

[host_machine]
system = 'linux'
subsystem = 'linux'
kernel = 'linux'
cpu_family = 'x86'
cpu = 'i686'
endian = 'little'
EOF

How to Use the File

Instead of setting environment variables before invoking meson setup .., you can simply do:

meson setup .. --cross-file lib32 <other-options>

Or...

meson setup .. --native-file x86 <other-options>