/* CR44 takes values 0 (head A), 3 (head B) and 4 (heads tied) * it affects only the 8 bit vga io regs, which we access using mmio at * 0xc{0,2}3c*, 0x60{1,3}3*, and 0x68{1,3}3d* * in general, the set value of cr44 does not matter: reg access works as * expected and values can be set for the appropriate head by using a 0x2000 * offset as required * however: * a) pre nv40, the head B range of PRMVIO regs at 0xc23c* was not exposed and * cr44 must be set to 0 or 3 for accessing values on the correct head * through the common 0xc03c* addresses * b) in tied mode (4) head B is programmed to the values set on head A, and * access using the head B addresses can have strange results, ergo we leave * tied mode in init once we know to what cr44 should be restored on exit * * the owner parameter is slightly abused: * 0 and 1 are treated as head values and so the set value is (owner * 3) * other values are treated as literal values to set */