During emerge, grub-static emits a warning about IA32_EMULATION but allows the install to continue. Afterwards, run_test_grub makes sure that the new binaries can be executed (so if you don't have IA32_EMULATION set, it isn't really a warning but an error). There's a new variable in -r10, $I_KNOW_WHAT_I_AM_DOING that skips the run_test_grub check for people who don't plan to actually run grub (e.g. me). It would be nice if it was mentioned somewhere so that we can skip the check if we_know_what_we_are_doing.
That is super internal variable that we don't want people to mess with. Mostly used by Gentoo devs to bypass some behaviour or by power users that wont open bugs afterwards. So it is not documented on purpose.
