After many searches, i'm quite astonished that i haven't find a real FDE solution for Linux (ie w/ encrypted boot partition)...
LFDE.org seems to suggest a solution but it isn't a real one (/boot partition is moved to a USB key) and reserved to Ubuntu for now.
I read this Wikipedia article
in order to find such a solution (w/ pre-boot auth so).
But can't really determine a complete solution.
Even being commercial, could someone advice me a real FDE solution (as so many existing for Windows) ?