Date: Thu, 29 Feb 1996 13:11:38 +0000
From: Ron Hochsprung <ron@apple.com>
Subject: Item #323: change to *output* definition

P1275 Openboot Working Group Proposal -- Proposal #:323 Ver 1

Title:          change to *output* definition

Author:         Ron Hochsprung

Date:           2/29/96

Ed/Tech:        Technical

Synopsis:       fix problem with *output* on PCI

Doc & Version:  none

Problem:

The current definition of *output* leaves the current output device open 
while attempting to open a new one.  On PCI, with multiple "VGA" display 
devices, this can cause multiple targets to respond, possibly crashing 
or hanging the system.

Proposal:

Define an alternative definition of *output* that would:
  1) save the pathname of the current output device.
  2) close the current output device
  3) attempt to open the new output device
  4) if successful, set the new output device as current.
  5) if the open of the new device fails, re-open the current device,
     using the pathname that was saved.

There may be alternative ways of dealing with the problem;  e.g., 
enforcing stricter requirments on what opened devices may have mapped in 
at any time.  However, I wanted to make sure that the problem gets 
addressed.

Ron


[ P1275 Item #323 -- Received: Thu Feb 29 13:09:33 PST 1996 ]