Cross compiling boost library for VxWorks

I am trying to cross compile the boost c++ library for VxWorks on Windows using cygwin (WindRiver workbench).
After running bootstrap.sh, I configured the project-config.jam for my cross compiler settings such,
using gcc : ppc : "<path to cross compiler on windows>" ;

Then i went on to execute
./b2 toolset=gcc-ppc target-os=linux

This was the recurrent message that I got for subsequent targets as they were being modified...



I thought passing threadapi=pthread as an option such,

./b2 toolset=gcc-ppc target-os=linux threadapi=pthread

would solve the first problem but the output remained the same.

Can anyone tell me what to do to get this working ?