386/ix, vt(7) & display(7) query.

[Larry Williamson]

    I have a need to access the video memory of a display adapter
directly.  This is supported with display(7) through the KDMAPDISP
ioctl.  I understand how to set up the display access.  I don't
understand what needs to be done before the VT_RELDISP ioctl. 

To have the video memory mapped into user space, the vt driver
must be in VT_PROCESS mode.  In this mode, when the user process
receives the appropriate signal, it is the responsiblity of the
the user process to save the "state" of the display and give
control back to the virtual terminal driver. 

The documentation on vt(7) says, "If the process desires to
release the device, it should save the device state (keyboard,
display, and I/O registers) and then do the VT_RELDISP ioctl..."

I don't understand how to save the device state.  What am I
supposed to save? I assume that I should save the video memory,
which is easy enough, but the keyboard and I/O registers? What am
I supposed to do here?

Any suggestions would be greatly appreciated. 

Regards,
    Larry

-- 
Larry Williamson  -- Focus Systems -- Waterloo, Ontario
                  watmath!focsys!larry  (519) 746-4918