      If the architecture is not supported but the platform provides <a class="link" href="ff/implementations__fcontext_t__ucontext_t_and_winfiber.html#implementation"><span class="emphasis"><em>ucontext_t</em></span></a>,
        <span class="bold"><strong>Boost.Context</strong></span> should be compiled with <code class="computeroutput"><span class="identifier">BOOST_USE_UCONTEXT</span></code> and b2 property <code class="computeroutput"><span class="identifier">context</span><span class="special">-</span