Gentoo's Bugzilla –
Attachment 318366 Details for
Bug 426898=app-emulation/virtualbox-modules-4.1.12 with sys-kernel/vanilla-sources-3.4.5 - src_test(): .../work/vboxdrv/r0drv/linux/memobj-r0drv-linux.c:1150:9: error: implicit declaration of function ‘do_mmap’