Determine if a kernel is built with a specific option?

[Eugene Grosbein]

> I was wondering how a autoconf configure script can determine if the
> kernel is built with a particular option. In this case the code I have
> can make use of the FreeBSD polling driver, which by default isn't
> built into a kernel. So I want my configure script to determine if the
> kernel supports it, if so sets a #define, otherwise doesn't.

You should not assume that compiled code does not need polling support
just because _buildbox_ doesn't have it enabled in time of build.
If the code builds here, it does not mean it will run here.

Eugene Grosbein