Cross-compile wxGtk

Question

I have to cross-compile wxGtk (an old version: 2.8.11) and managed to setup the environment so that configure runs successfully.

$ export CC=/opt/my_toolchain/toolchain_base/bin/i686-pc-linux-gnu-gcc
$ export CXX=/opt/my_toolchain/toolchain_base/bin/i686-pc-linux-gnu-g++
$ export CPPFLAGS=-I/opt/my_toolchain/additional_libs/usr/include/
$ export PKG_CONFIG_SYSROOT_DIR=/opt/my_toolchain/additional_libs/
$ export PKG_CONFIG_PATH=/opt/my_toolchain/additional_libs/usr/lib/pkgconfig
$ export PKG_CONFIG_DIR=/opt/my_toolchain/additional_libs/usr/lib/pkgconfig
$ export PKG_CONFIG_LIBDIR=/opt/my_toolchain/additional_libs/sysroot/usr/lib/
// LDFLAGS evtl falsch?? nicht ueberschreiben!?
$ export LDFLAGS="-L/opt/my_toolchain/additional_libs/lib/ -L/opt/my_toolchain/additional_libs/usr/lib/"
$ export CFLAGS="-Wl,-rpath-link=/opt/my_toolchain/additional_libs/lib/ -Wl,-rpath-link=/opt/my_toolchain/additional_libs/usr/lib/"
$ export CXXFLAGS="-Wl,-rpath-link=/opt/my_toolchain/additional_libs/lib/ -Wl,-rpath-link=/opt/my_toolchain/additional_libs/usr/lib/"
$ export LD_LIBRARY_PATH=/opt/my_toolchain/additional_libs/lib/:/opt/my_toolchain/additional_libs/usr/lib/:/opt/my_toolchain/additional_libs/usr/lib/:/opt/my_toolchain/additional_libs/lib/
$ pkg-config --define-variable=pc_path=/opt/my_toolchain/additional_libs/usr/lib/pkgconfig pkg-config

wxGTK-2.8.11 $ ./configure --enable-unicode --disable-shared --prefix=/usr/local/<targetname>
[...]
Configured wxWidgets 2.8.11 for `x86_64-unknown-linux-gnu'

Which GUI toolkit should wxWidgets use?                 GTK+ 2
Should wxWidgets be compiled into single library?       no
Should wxWidgets be compiled in debug mode?             no
Should wxWidgets be linked as a shared library?         no
Should wxWidgets be compiled in Unicode mode?           yes
What level of wxWidgets compatibility should be enabled?
                                   wxWidgets 2.4      no
                                   wxWidgets 2.6      yes
Which libraries should wxWidgets use?
                                   jpeg               sys
                                   png                sys
                                   regex              builtin
                                   tiff               sys
                                   zlib               sys
                                   odbc               no
                                   expat              sys
                                   libmspack          no
                                   sdl                no

However the subsequent make reports an error:

wxGTK-2.8.11 $ make
[...]
bk-make-pch ./.pch/wxprec_netlib/wx/wxprec.h.gch wx/wxprec.h /opt/my_toolchain/toolchain_base/bin/i686-pc-linux-gnu-g++ -I./.pch/wxprec_netlib -D__WXGTK__     -DWXBUILDING      -I./src/regex  -DwxUSE_GUI=0 -D_FILE_OFFSET_BITS=64 -D_LARGE_FILES -I/mnt/cifs/osb_m/10_Competence_Centers/21_CC_IE/22_Kunden_Technik_Aktiv/Holmer/Software/Holmer_VT-Server/wxGTK-2.8.11/lib/wx/include/gtk2-unicode-release-static-2.8 -I./include -pthread -I/opt/my_toolchain/additional_libs//usr/include/gtk-2.0 -I/opt/my_toolchain/additional_libs//usr/lib/gtk-2.0/include -I/opt/my_toolchain/additional_libs//usr/include/pango-1.0 -I/opt/my_toolchain/additional_libs//usr/include/atk-1.0 -I/opt/my_toolchain/additional_libs//usr/include/cairo -I/opt/my_toolchain/additional_libs//usr/include/pixman-1 -I/opt/my_toolchain/additional_libs//usr/include/libpng16 -I/opt/my_toolchain/additional_libs//usr/include/gdk-pixbuf-2.0 -I/opt/my_toolchain/additional_libs//usr/include/libpng16 -I/opt/my_toolchain/additional_libs//usr/include/pango-1.0 -I/opt/my_toolchain/additional_libs//usr/include/harfbuzz -I/opt/my_toolchain/additional_libs//usr/include/pango-1.0 -I/opt/my_toolchain/additional_libs//usr/include/freetype2 -I/opt/my_toolchain/additional_libs//usr/include/glib-2.0 -I/opt/my_toolchain/additional_libs//usr/lib/glib-2.0/include -I/opt/my_toolchain/additional_libs/usr/include/ -DWX_PRECOMP -pthread -Wall -Wundef -Wno-ctor-dtor-privacy -O2 -fno-strict-aliasing -Wl,-rpath-link=/opt/my_toolchain/additional_libs/lib/ -Wl,-rpath-link=/opt/my_toolchain/additional_libs/usr/lib/
In file included from /opt/my_toolchain/additional_libs/usr/include/math.h:46:0,
             from ./include/wx/math.h:19,
             from ./include/wx/wx.h:30,
             from ./include/wx/wxprec.h:68:
/opt/my_toolchain/additional_libs/usr/include/bits/mathdef.h:47:6: warning: "__FP_FAST_FMA" is not defined [-Wundef]
/opt/my_toolchain/additional_libs/usr/include/bits/mathdef.h:51:6: warning: "__FP_FAST_FMAF" is not defined [-Wundef]
/opt/my_toolchain/additional_libs/usr/include/bits/mathdef.h:55:6: warning: "__FP_FAST_FMAL" is not defined [-Wundef]
/opt/my_toolchain/toolchain_base/bin/../i686-pc-linux-gnu/libc/usr/lib/crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: error: ld returned 1 exit status
Makefile:12022: recipe for target '.pch/wxprec_netlib/wx/wxprec.h.gch' failed
make: *** [.pch/wxprec_netlib/wx/wxprec.h.gch] Error 1

I've printed the compiler command which reports the issue:

/opt/my_toolchain/toolchain_base/bin/i686-pc-linux-gnu-g++ \
-I./.pch/wxprec_baselib -D__WXGTK__ -DWXBUILDING \
-I./src/regex \
-DwxUSE_GUI=0 -DwxUSE_BASE=1 -D_FILE_OFFSET_BITS=64 -D_LARGE_FILES \
-I/path/to/wxGTK-2.8.11/lib/wx/include/gtk2-unicode-release-static-2.8 \
-I./include \
-pthread \
-I/opt/my_toolchain/additional_libs//usr/include/gtk-2.0 \
-I/opt/my_toolchain/additional_libs//usr/lib/gtk-2.0/include \
-I/opt/my_toolchain/additional_libs//usr/include/pango-1.0 \
-I/opt/my_toolchain/additional_libs//usr/include/atk-1.0 \
-I/opt/my_toolchain/additional_libs//usr/include/cairo \
-I/opt/my_toolchain/additional_libs//usr/include/pixman-1 \
-I/opt/my_toolchain/additional_libs//usr/include/libpng16 \
-I/opt/my_toolchain/additional_libs//usr/include/gdk-pixbuf-2.0 \
-I/opt/my_toolchain/additional_libs//usr/include/libpng16 \
-I/opt/my_toolchain/additional_libs//usr/include/pango-1.0 \
-I/opt/my_toolchain/additional_libs//usr/include/harfbuzz \
-I/opt/my_toolchain/additional_libs//usr/include/pango-1.0 \
-I/opt/my_toolchain/additional_libs//usr/include/freetype2 \
-I/opt/my_toolchain/additional_libs//usr/include/glib-2.0 \
-I/opt/my_toolchain/additional_libs//usr/lib/glib-2.0/include \
-I/opt/my_toolchain/additional_libs/usr/include/ \
-DWX_PRECOMP -pthread -Wall -Wundef -Wno-ctor-dtor-privacy -O2 -fno-strict-aliasing \
-Wl,-rpath-link=/opt/my_toolchain/additional_libs/lib/ \
-Wl,-rpath-link=/opt/my_toolchain/additional_libs/usr/lib/ \
-o ./.pch/wxprec_baselib/wx/wxprec.h.gch \
-MMD -MF \
./.deps/___pch_wxprec_baselib_wx_wxprec_h_gch.d \
./include/wx/wxprec.h

If I remove the two the -Wl,-rpath-link= statements from this compiler command and invoke it manually, the command succeeds.

It seems the additional -Wl statements make the compiler miss the source file with the main() -function (which seems to be provided via ./include/wx/wxprec.h ), but I don't really see how that could happen.

I'd be grateful about any advice how I can address this problem.

Update

The configure -Script has the usual options (no --source )

--build=BUILD     configure for building on BUILD [guessed]
--host=HOST       cross-compile to build programs to run on HOST [BUILD]
--target=TARGET   configure for building compilers for TARGET [HOST]

where --target is of no interest. The other options I'll have to check. As I mentioned in the comments, I've so far only seen them being used with prefixes eg aarch64-linux-gnu for toolchains from package repositories which are in the $PATH , and with according libraries etc.

So I've added the folder for toolchain binaries to path and configured with

./configure --enable-unicode --disable-shared --prefix=/usr/local/<target> --host=i686-pc-linux-gnu


configure: WARNING: If you wanted to set the --build type, don't use --host.
If a cross compiler is detected then cross compile mode will be used.
checking build system type... x86_64-unknown-linux-gnu
checking host system type... i686-pc-linux-gnu
checking target system type... i686-pc-linux-gnu

That looks correct. I want to build on my local machine for another target.

But:

checking for GTK+ - version >= 2.0.0... no
*** Could not run GTK+ test program, checking why...
*** The test program failed to compile or link. See the file config.log for the
*** exact error that occured. This usually means GTK+ is incorrectly installed.
configure: error:
The development files for GTK+ were not found. For GTK+ 2, please
ensure that pkg-config is in the path and that gtk+-2.0.pc is
installed. For GTK+ 1.2 please check that gtk-config is in the path,
and that the version is 1.2.3 or above. Also check that the
libraries returned by 'pkg-config gtk+-2.0 --libs' or 'gtk-config
--libs' are in the LD_LIBRARY_PATH or equivalent.

Unfortunately that makes sense. The toolchain itself only has some libraries, but does not have the GTK-libraries.

/opt/my_toolchain/toolchain_base/

The GTK libraries and other libraries are in a separate folder:

/opt/my_toolchain/additional_libs/

And the toolchain's binaries don't know about this folder.

I think the whole issue arises because wxGtk builds libraries for the host = i686-pc-linux-gnu , but also builds executables (eg wx-config ) for the build-system = x86_64-unknown-linux-gnu .

Answer 1

The wxGtk 2.8.11 cross-build is finally working with the following setup:

export PATH=/opt/my_toolchain/toolchain_base/bin/:${PATH}
export PKG_CONFIG_SYSROOT_DIR=/opt/my_toolchain/additional_libs
export PKG_CONFIG_PATH=/opt/my_toolchain/additional_libs/usr/lib/pkgconfig
export PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=1
# make sure those env vars are not left from previous setup
unset  CC
unset  CXX
unset  CPPFLAGS
unset  CFLAGS
unset  CXXFLAGS
unset  LD_LIBRARY_PATH
unset  LDFLAGS
unset  PKG_CONFIG_DIR
unset  PKG_CONFIG_LIBDIR

./configure --enable-unicode --disable-shared --prefix=/usr/local/<target> --host=i686-pc-linux-gnu --build=x86_64-linux-gnu
make
sudo make install