NAME

vdm − video memory map

SYNOPSIS

#include <sys/kd.h>
#include <sys/vdm.h>

DESCRIPTION

vdm is a pseudo-device driver used to map the memory of a bitmapped display into the virtual address space of a process.  It is currently used only for the Cornerstone Video Controller X11 server (see Xcvc(1)), but the interface is general and may be used to map memory for other devices.

The driver supports only the single ioctl VDM_MAP to map a region of physical memory.  The argument to the ioctl must be a pointer to a struct kd_memloc (see KDMAPDISP in display(7)). The vaddr and length elements of the structure must specify a valid address range within the process address space.  (A process may use malloc(3) to allocate the area. This will not consume actual memory as long as the memory is not accessed until after it has been mapped.)  The phys­addr must be the location of the physical memory for the device.  vdm will refuse to map to memory already in use by the kernel.  The ioflg element of the structure is ignored. 

The effective user ID of the process must be root (the superuser) to use this device. 

FILES

/dev/vdm

SEE ALSO

Xcvc(1). 
malloc(3C) in the INTERACTIVE SDS Guide and Programmer’s Reference Manual.

\*U  —  Version 1.0