Date: Sun, 01 Nov 1998 20:31:24 +0900 From: Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp> To: Christopher Masto <chris@netmonger.net> Cc: hackers@FreeBSD.ORG, yokota@zodiac.mech.utsunomiya-u.ac.jp Subject: Re: Some curiosity about syscons Message-ID: <199811011131.UAA15844@zodiac.mech.utsunomiya-u.ac.jp> In-Reply-To: Your message of "Mon, 26 Oct 1998 23:02:08 EST." <19981026230208.A8159@netmonger.net> References: <19981026230208.A8159@netmonger.net>
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[...] >Rather than back up and start over with a different approach, I added >a tiny ioctl to syscons to call scrn_update(). With that and some >fudging, I actually have the damned thing working. Um, scrn_update() can be called on certain conditions. See scrn_timer() for correct timing. All in all, it is very difficult to guarantee that the screen is update at precisely 60Hz. >If anyone is still following this, and particularly if you Know From >Experience, perhaps you can comment on some of these architectural >issues. I need a 60Hz vertical refresh rate, and I need to be able to >display 18 lines of text every frame. This needs to happen during the >vertical retrace interval, as a single glitched frame will cause a >failure. Ideally I would like the cursor not to be present, but it >isn't actually a problem if I can make sure it is always at the top or >bottom of the screen. You have to poll a CRTC status port for vertical retrace period. As Mike has already suggested, it is probably best to do this sort of things as a screen saver LKM. The screen saver can do whatever it wants (just like DOS programs... :-) The tricky thing is that syscons will instantly deactivate the screen saver LKM as soon as a key is pressed (or mouse is moved). Kazu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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