Do NOT use "-b" unless you really know what it is for.
The -b switch will cause bitbake to just build the recipe in the single .bb file. This means that if it has any dependencies (including the toolchain, etc.), these will not be built and therefore your build may well fail.
The -b option is mainly for developers who want to try to rebuild a package quickly after modifying it (i.e. after they have already run a full bitbake for it and know the deps are present). It is far faster to re-build the single package this way as it only parses the .bb file that you pass it.
Hope that makes things a bit clearer,
Si