/etc/portage/profile/use.mask

Some USE flags do not make sense on certain architectures (for example the  flag on a non-PPC architecture or the   on a non- system). Other times certain USE flag configurations have not yet been tested. Here the masked ones USE flags are masked. The file is available to mask configurations that could potentially break the system.

Format

 * Comments begin with  (no inline comments).
 * One USE flag per line.