this is what glxinfo says about the visuals available:
visual x bf lv rg d st colorbuffer ax dp st accumbuffer ms cav id dep cl sp sz l ci b ro r g b a bf th cl r g b a ns b eat ---------------------------------------------------------------------- 0x23 24 tc 0 32 0 r . . 8 8 8 8 0 24 0 0 0 0 0 0 0 None 0x24 24 tc 0 32 0 r . . 8 8 8 8 0 24 8 0 0 0 0 0 0 None 0x25 24 tc 0 32 0 r . . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow 0x26 24 tc 0 32 0 r . . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow 0x27 24 tc 0 32 0 r y . 8 8 8 8 0 24 0 0 0 0 0 0 0 None 0x28 24 tc 0 32 0 r y . 8 8 8 8 0 24 8 0 0 0 0 0 0 None 0x29 24 tc 0 32 0 r y . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow 0x2a 24 tc 0 32 0 r y . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow 0x2b 24 dc 0 32 0 r . . 8 8 8 8 0 24 0 0 0 0 0 0 0 None 0x2c 24 dc 0 32 0 r . . 8 8 8 8 0 24 8 0 0 0 0 0 0 None 0x2d 24 dc 0 32 0 r . . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow 0x2e 24 dc 0 32 0 r . . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow 0x2f 24 dc 0 32 0 r y . 8 8 8 8 0 24 0 0 0 0 0 0 0 None 0x30 24 dc 0 32 0 r y . 8 8 8 8 0 24 8 0 0 0 0 0 0 None 0x31 24 dc 0 32 0 r y . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow 0x32 24 dc 0 32 0 r y . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow 0x4b 32 tc 0 32 0 r . . 8 8 8 8 0 0 0 0 0 0 0 0 0 Ncon
this is what glxinfo says about the visuals available:
visual x bf lv rg d st colorbuffer ax dp st accumbuffer ms cav ------- ------- ------- ------- ------- ------- ------- ------- -------
id dep cl sp sz l ci b ro r g b a bf th cl r g b a ns b eat
-------
0x23 24 tc 0 32 0 r . . 8 8 8 8 0 24 0 0 0 0 0 0 0 None
0x24 24 tc 0 32 0 r . . 8 8 8 8 0 24 8 0 0 0 0 0 0 None
0x25 24 tc 0 32 0 r . . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow
0x26 24 tc 0 32 0 r . . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow
0x27 24 tc 0 32 0 r y . 8 8 8 8 0 24 0 0 0 0 0 0 0 None
0x28 24 tc 0 32 0 r y . 8 8 8 8 0 24 8 0 0 0 0 0 0 None
0x29 24 tc 0 32 0 r y . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow
0x2a 24 tc 0 32 0 r y . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow
0x2b 24 dc 0 32 0 r . . 8 8 8 8 0 24 0 0 0 0 0 0 0 None
0x2c 24 dc 0 32 0 r . . 8 8 8 8 0 24 8 0 0 0 0 0 0 None
0x2d 24 dc 0 32 0 r . . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow
0x2e 24 dc 0 32 0 r . . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow
0x2f 24 dc 0 32 0 r y . 8 8 8 8 0 24 0 0 0 0 0 0 0 None
0x30 24 dc 0 32 0 r y . 8 8 8 8 0 24 8 0 0 0 0 0 0 None
0x31 24 dc 0 32 0 r y . 8 8 8 8 0 24 0 16 16 16 16 0 0 Slow
0x32 24 dc 0 32 0 r y . 8 8 8 8 0 24 8 16 16 16 16 0 0 Slow
0x4b 32 tc 0 32 0 r . . 8 8 8 8 0 0 0 0 0 0 0 0 0 Ncon