Created attachment 287833 [details] The config used with .39 and .32 The bt8xx drivers are not selectable with gentoo-sources-2.6.39-r3. Downgrading to gentoo-sources-2.6.32-gentoo-r29 solves the issue and bt848 can be selected and compiled.
The problem seems to be that BT8xx drivers depend on Remote Controller adapters (RC_CORE)