Date: Fri, 12 Nov 1999 00:54:46 -0800 From: Mike Smith <mike@smith.net.au> To: Amancio Hasty <hasty@rah.star-gate.com> Cc: current@FreeBSD.ORG Subject: Re: vga driver and signal Message-ID: <199911120854.AAA00712@dingo.cdrom.com> In-Reply-To: Your message of "Thu, 04 Nov 1999 19:05:41 PST." <199911050305.TAA50795@rah.star-gate.com>
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> > > > The only real way to do this "right" is going to be to have the X > > > > server load a KLD, which will then be able to hook the relevant > > > > interrupt(s). Any other alternative involves interrupt delivery to > > > > user-space, which is just not practical. > > > > > > Hi Mike, > > > Your idea sounds intriguing . How should we wired the KLD to > > > the X server? or how will the KLD inform the X server that it > > > has received a vertical retrace interrupt . > > > > The X server would have to load the KLD when it starts. The KLD would > > have to contain _all_ of the code that would run when the interrupt > > triggered. You would still have absolutely no latency guarantee on > > delivery of the interrupt to the KLD; you'd have to check on entry to > > the handler to see whether you weren't already too late. > > > > Basically, the whole idea is just totally screwed. You shouldn't be > > trying to do this because it just can't be done right. > > I should be trying to do this for it can have interesting applications such > as a Tivo player. Not sure what the problem with interrupt latency is ... > Can you elaborate a little bit more ? If you're talking about a specific piece of hardware whose design you are in control of, you can tweak the hardware/software combination to achieve the desired goal. The point I was trying to make was that in the _general_ case, this can't be done with software alone. You require the cooperation of hardware that just can't be obtained from your average PC. -- \\ Give a man a fish, and you feed him for a day. \\ Mike Smith \\ Tell him he should learn how to fish himself, \\ msmith@freebsd.org \\ and he'll hate you for a lifetime. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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