4.3BSD-UWisc/man/cat4/ik.4

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IK(4)               UNIX Programmer's Manual                IK(4)



NAME
     ik - Ikonas frame buffer, graphics device interface

SYNOPSIS
     device ik0 at uba? csr 0172460 vector ikintr

DESCRIPTION
     _I_k 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 over-
     head.

     Bytes written or read from the device are DMA'ed from or to
     the interface.  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.

















Printed 12/27/86          May 15, 1985                          1