[ubuntu] ubuntu and osx full disk encryption easily possible? what about dual graphics?

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http://ubuntuforums.org – hello, i got a macbook pro 9,1 (mid 2012) and plan on finally switching from osx as main system and windows for games, to ubuntu as main one and osx just for firmware updates. how would i do that, while still being able to use the full disk encryption from the ubuntu installer (so easy). because last time i tried, w/ my osx volume fully encrypted, w/ recovery, ubuntu would only let me use fde, if i had erased the whole disk again and started over. osx full disk encryption isn't really needed, if i plan on just keeping it around for updates to the hardware. or would you just kill osx (Hardware)