opts.Add(ListVariable('drivers', 'pipe drivers to build', default_drivers,
['softpipe', 'failover', 'svga', 'i915', 'i965', 'trace', 'r300', 'r600', 'identity', 'llvmpipe', 'nouveau', 'nv50', 'nvfx']))
opts.Add(ListVariable('winsys', 'winsys drivers to build', default_winsys,
opts.Add(ListVariable('drivers', 'pipe drivers to build', default_drivers,
['softpipe', 'failover', 'svga', 'i915', 'i965', 'trace', 'r300', 'r600', 'identity', 'llvmpipe', 'nouveau', 'nv50', 'nvfx']))
opts.Add(ListVariable('winsys', 'winsys drivers to build', default_winsys,