cross-compile Qt 5.5 for iMX6 - with or without -no-gcc-sysroot?

[m_andrej]

Hi,
I'm trying to cross-compile Qt 5.5 for iMX6 (Phytec board with Yocto). I have two questions:

• can I use g++ compiler from Ubuntu package g++-arm-linux-gnueabi, or do I have to download Linaro?
• should I run configure with -no-gcc-sysroot?

At the moment configure fails both with and without -no-gcc-sysroot, but with slightly different error messages related to OpenGL ES 2.0. My configure call looks like this:

../5.5/Src/configure 
-opensource 
-confirm-license 
-release 
-eglfs 
-no-pch 
-no-xcb 
-no-opengl 
-opengl es2 
-make libs 
-nomake tests 
-nomake examples 
-device imx6 
-xplatform linux-arm-gnueabi-g++ 
-sysroot /opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi 
-prefix /usr/lib/Qt-5.5  
-v

When -no-gcc-sysroot is excluded as above, library paths to sysroot are propagated to DEFAULT_INCDIRS and DEFAULT_LIBDIRS:

arm-linux-gnueabi-g++ --sysroot=/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi -o libtest.so -shared -Wl,-Bsymbolic-functions -fPIC bsymbolic_functions.c
bsymbolic_functions.c:2:2: error: #error "Symbolic function binding on this architecture may be broken, disabling it (see QTBUG-36129)."
Symbolic function binding disabled.
DEFAULT_INCDIRS="/usr/lib/gcc-cross/arm-linux-gnueabi/4.7/include
/usr/lib/gcc-cross/arm-linux-gnueabi/4.7/include-fixed
/usr/arm-linux-gnueabi/include
/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi/usr/include
"
DEFAULT_LIBDIRS="/usr/arm-linux-gnueabi/lib
/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi/lib
/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi/usr/lib
/usr/lib/gcc-cross/arm-linux-gnueabi/4.7
"

Failing linker step prints the following output:

arm-linux-gnueabi-g++ -Wl,-O1 -o opengles2 opengles2.o   --sysroot=/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi -lGLESv2 
/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi/lib/libpthread.so.0: undefined reference to `__default_rt_sa_restorer@GLIBC_PRIVATE'
/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi/lib/libpthread.so.0: undefined reference to `__default_sa_restorer@GLIBC_PRIVATE'
/opt/yogurt/iMX6-PD15.1.0/sysroots/cortexa9hf-vfp-neon-phytec-linux-gnueabi/lib/libpthread.so.0: undefined reference to `__libc_vfork@GLIBC_PRIVATE'
collect2: error: ld returned 1 exit status

With -no-gcc-sysroot, environment variables are missing paths to sysroot and linker prints this output:

arm-linux-gnueabi-g++ -Wl,-O1 -o opengles2 opengles2.o   -lGLESv2 
/usr/lib/gcc-cross/arm-linux-gnueabi/4.7/../../../../arm-linux-gnueabi/bin/ld: cannot find -lGLESv2

I have libgles2-mesa-dev package installed on the host OS (don't know if it matters).