Date: Fri, 8 Aug 1997 13:55:45 -0700 (MST) From: Terry Lambert <terry@lambert.org> To: perlsta@sunyit.edu (Alfred Perlstein) Cc: hackers@FreeBSD.ORG Subject: Re: reset screen hardware? Message-ID: <199708082055.NAA27986@phaeton.artisoft.com> In-Reply-To: <Pine.BSF.3.96.970808125605.680B-100000@server.local.sunyit.edu> from "Alfred Perlstein" at Aug 8, 97 12:59:19 pm
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> Last night X crashed on me, i thought my machine needed to be rebooted, > but first i tried to telnet into it, i was able and i killed X and had to > restart X twice to get it to work, well everything seemed fine after that, > however my Text consols were all fubar'd and i had no idea how to reset > the text part of my display to i wound up rebooting anyway. > > What could i have done to reset the text screens? You could have modified X to use a DDX in the kernel so that when the X server was killed, the kernel driver would be able to restore the video card to the pre-X server state. Failing that, the console driver has no idea what the X server has done to the I/O ports and video card reigsters; not knowing what was done to the card means it can't know how to undo it. So, you could have tried to less destructively kill the X server (kill -1 or -15 instead of -9) and prayed the signal handler did the cleanup. If it didn't, there was nothing you could do, period. This is a basic problem with the design of the X-server/video card interface for user space X server code. Nothing short of a redesign can really fix it. By the same token, the kernel debugger can't restore the video state when you drop into the kernel debugger from X in the event of a fault or debugging trap. This is one of my most long-standing gripes with UNIX systems since the first days of X windows. 8-(. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.
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