https://bugs.freedesktop.org/show_bug.cgi?id=57875
--- Comment #8 from Alex Deucher agd5f@yahoo.com --- (In reply to comment #7)
Aw, of course thr R3xx_3D_Registers.pdf document doesn't document bit 24 of R300_GB_TILE_CONFIG, which supposedly contains the Z_EXTENDED flag...
That bit only exists on r5xx asics. R3xx and r4xx don't have that bit.