From the Academy of Motion Picture Arts and Sciences website:
NOMINATIONS VOTING PROCESS
Regular awards are presented for outstanding individual or collective film achievements in a wide variety of categories. Most categories are nominated by the members of the corresponding branch-actors nominate actors, film editors nominate film editors, etc. However, certain categories such as Foreign Language Film and Animated Feature Film have special voting rules which can be viewed at our Rules & Eligibility page.
All voting members are eligible to select the Best Picture nominees.
Nominations voting is conducted using both paper and online ballots, with online voting being the preferred choice for the overwhelming majority of Academy members. Voting for nominations begins in late December, and all votes are tabulated by PricewaterhouseCoopers.
Nomination results are then announced at a live televised press conference in mid-January at the Academy's Samuel Goldwyn Theater in Beverly Hills.
So they would really be boycotting each other, not some secret star chamber that only nominates white people.
-PJ
Like the commercial, "I can't wait to stick it to 'The Man.'"
"But sir, you are 'The Man', so you'd be sticking it to yourself."