IK(4)                  OpenBSD Programmer's Manual (VAX)                 IK(4)

NAME
     ik - Ikonas frame buffer, graphics device interface

SYNOPSIS
     device ik0 at uba? csr 0172460 vector ikintr

DESCRIPTION
     The ik driver 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 virtu-
     al memory, into the user processes address space.  This allows the user
     process very high bandwidth to the frame buffer with no system call over-
     head.

     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(2) returns the virtual address where the user process can find the
     interface registers.  The IK_WAITINT ioctl suspends the user process un-
     til the ikonas device has interrupted (for whatever reason -- the user
     process has to set the interrupt enables).

FILES
     /dev/ik

DIAGNOSTICS
     None.

HISTORY
     The ik driver appeared in 4.2BSD.

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.

OpenBSD 3.0                     March 27, 1991                               1
