## Cross-compiling the GLib package

Cross-compiling the GLib Package — How to cross-compile GLib

## 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 autoconf 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 the configure script via a "cache file" or by setting the cache variables in your environment.

As an example of using a cache file, to cross compile for the "MingW32" Win32 runtine environment on a Linux system, create a file 'win32.cache' with the following contents:

    glib_cv_long_long_format=ll
    glib_cv_stack_grows=no

Then execute the following commands:

    PATH=/path/to/mingw32-compiler/bin:$PATH
    chmod a-w win32.cache   # prevent configure from changing it
    ./configure --cache-file=win32.cache --host=mingw32

The complete list of cache file variables follows. Most of these won't need to be set in most cases.

## Cache file variables

glib_cv_long_long_format=[ll/q/I64]. Format used by `printf()` and `scanf()` for 64 bit integers. "ll" is the C99 standard, and what is used by the 'trio' library that GLib builds if your `printf()` is insufficiently capable. Doesn't need to be set if you are compiling using trio.

glib_cv_stack_grows=[yes/no]. Whether the stack grows up or down. Most places will want "no", A few architectures, such as PA-RISC need "yes".

glib_cv_working_bcopy=[yes/no]. Whether your `bcopy()` can handle overlapping copies. Only needs to be set if you don't have `memmove()`. (Very unlikely)

glib_cv_sane_realloc=[yes/np]. Whether your `realloc()` conforms to ANSI C and can handle `NULL` as the first argument. Defaults to "yes" and probably doesn't need to be set.

glib_cv_have_strlcpy=[yes/no]. Whether you have `strlcpy()` that matches OpenBSD. Defaults to "no", which is safe, since GLib uses a built-in version in that case.

glib_cv_va_val_copy=[yes/no]. Whether va_list can be copied as a pointer. If set to "no", 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 "yes" which is slightly more common than "no".

glib_cv_rtldglobal_broken=[yes/no]. Whether you have a bug found in OSF/1 v5.0. Defaults to "no".

glib_cv_uscore=[yes/no]. Whether an underscore needs to be prepended to symbols when looking them up via `dlsym()`. Only needs to be set if your system uses `dlopen()`/`dlsym()`.

ac_cv_func_posix_getpwuid_r=[yes/no]. Whether you have a getpwuid_r function (in your C library, not your thread library) that conforms to the POSIX spec. (Takes a 'struct passwd **' as the final argument)

ac_cv_func_nonposix_getpwuid_r=[yes/no]. Whether you have some variant of `getpwuid_r()` that doesn't conform to to the POSIX spec, but GLib might be able to use (or might segfault.) Only needs to be set if `ac_cv_func_posix_getpwuid_r` is not set. It's safest to set this to "no".

glib_cv_use_pid_surrogate=[yes/no]. Whether to use a `setpriority()` on the PID of the thread as a method for setting the priority of threads. This only needs to be set when using POSIX threads.

ac_cv_func_printf_unix98=[yes/no]. Whether your `printf()` family supports Unix98 style `%N$` positional parameters. Defaults to "no".

ac_cv_func_vsnprintf_c99=[yes/no]. 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 "no".