4.3BSD - /usr/man/cat4/ik.0

IK(4)                                                                    IK(4)


NAME
       ik - Ikonas frame buffer, graphics device interface

SYNOPSIS
       device ik0 at uba? csr 0172460 vector ikintr

DESCRIPTION
       Ik  provides  an  interface  to an Ikonas frame buffer graphics device.
       Each minor device is a different frame buffer  interface  board.   When
       the  device  is opened, its interface registers are mapped, via virtual
       memory, into the user processes address space.  This  allows  the  user
       process  very  high  bandwidth  to the frame buffer with no system call
       overhead.

       Bytes written or read from the device are DMA’ed from or to the  inter‐
       face.   The  frame buffer XY address, its addressing mode, etc. must be
       set up by the user process before calling write or read.

       Other communication with the driver  is  via  ioctls.   The  IK_GETADDR
       ioctl  returns  the virtual address where the user process can find the
       interface registers.  The IK_WAITINT ioctl suspends  the  user  process
       until the ikonas device has interrupted (for whatever reason — the user
       process has to set the interrupt enables).

FILES
       /dev/ik

DIAGNOSTICS
       None.

BUGS
       An invalid access (e.g., longword) to a mapped interface  register  can
       cause  the  system to crash with a machine check.  A user process could
       possibly cause infinite interrupts hence bringing things to a crawl.


4.2 Berkeley Distribution        May 15, 1985                            IK(4)