Date: Thu, 11 Jun 1998 07:07:51 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: mike@smith.net.au (Mike Smith) Cc: mike@smith.net.au, current@FreeBSD.ORG Subject: Re: floating point usage within the kernel - howto ? Message-ID: <199806110507.HAA21914@labinfo.iet.unipi.it> In-Reply-To: <199806110524.WAA01035@antipodes.cdrom.com> from "Mike Smith" at Jun 10, 98 10:24:27 pm
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> > task to the timer interrupt. I am trying to push them to use FreeBSD > > (and an LKM for this module) so that they can easily access the > > controller across the network or via the web, use high level stuff > > for visualization, etc. > > A worthy goal. They're not interested in using a "real" motor > controller card? they do it for real stuff of course but this opens other problems like the sw. development which usually runs under dos/windows (what else!), communicating withthe controller across a serial line, etc. > > For sure they can do fixed point, but if i can find a solution for > > 'save_fp_regs()/restore_fp_regs()' this might have other uses as well. > > The problem is mostly just one of dealing with the FP context switch; ok, i will browse through the sources. i have seen a reference to npxsave which could help. > IMHO, you'd be better of with them using rtprio() and running the > control applicaton in user-space, especially if they were previously > using the 18Hz timer resolution. It doesn't sound like anything other > than the hardware access needs to be in the kernel at all. that's an alternative but i am just not sure how much overhead there would be (we plan to use up to HZ=1000 and run at every tick; the original application used to run at 100-200 hz they are telling me, using a timer on the AD/DA card.) thanks luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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