Building the Library for a different architecture

Cross-compilation is the process of compiling a program or library on a different architecture or operating system then it will be run upon. GLib is slightly more difficult to cross-compile than many packages because much of GLib is about hiding differences between different systems.

These notes cover things specific to cross-compiling GLib; for general information about cross-compilation, see the meson info pages.

GLib tries to detect as much information as possible about the target system by compiling and linking programs without actually running anything; however, some information GLib needs is not available this way. This information needs to be provided to meson via a ‘cross file’.

As an example of using a cross file, to cross compile for the ‘MingW32’ Win64 runtime environment on a Linux system, create a file cross_file.txt with the following contents:

 
[host_machine]
system = 'windows'
cpu_family = 'x86_64'
cpu = 'x86_64'
endian = 'little'

[properties]
c_args = []
c_link_args = []

[binaries]
c = 'x86_64-w64-mingw32-gcc'
cpp = 'x86_64-w64-mingw32-g++'
ar = 'x86_64-w64-mingw32-ar'
ld = 'x86_64-w64-mingw32-ld'
objcopy = 'x86_64-w64-mingw32-objcopy'
strip = 'x86_64-w64-mingw32-strip'
pkgconfig = 'x86_64-w64-mingw32-pkg-config'
windres = 'x86_64-w64-mingw32-windres'
      

Then execute the following commands:

meson --cross-file cross_file.txt builddir
      

The complete list of cross properties follows. Most of these won't need to be set in most cases.

Cross properties

have_[function].  When meson checks if a function is supported, the test can be overridden by setting the have_function property to true or false. For example

Checking for function "fsync" : YES

can be overridden by setting

have_fsync = false

growing_stack=[true/false].  Whether the stack grows up or down. Most places will want false. A few architectures, such as PA-RISC need true.

have_strlcpy=[true/false].  Whether you have strlcpy() that matches OpenBSD. Defaults to false, which is safe, since GLib uses a built-in version in that case.

va_val_copy=[true/false].  Whether va_list can be copied as a pointer. If set to false, then memcopy() will be used. Only matters if you don't have va_copy() or __va_copy(). (So, doesn't matter for GCC.) Defaults to true which is slightly more common than false.

have_c99_vsnprintf=[true/false].  Whether you have a vsnprintf() with C99 semantics. (C99 semantics means returning the number of bytes that would have been written had the output buffer had enough space.) Defaults to false.

have_c99_snprintf=[true/false].  Whether you have a snprintf() with C99 semantics. (C99 semantics means returning the number of bytes that would have been written had the output buffer had enough space.) Defaults to false.