Date: Thu, 14 Nov 1996 06:35:35 +1100 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, sos@ravenock.cybercity.dk Cc: freebsd-current@freebsd.org, jkh@time.cdrom.com, nate@mt.sri.com, wangel@wgrobez1.remote.louisville.edu Subject: Re: your mail Message-ID: <199611131935.GAA13980@godzilla.zeta.org.au>
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>> - check for psm interrupt and don't poll keyboard if one is pending OR > >which bits to poll for that ??, and its difficult to know if a keyboard >int has been lost already, so who's data is it we're reading... The psm bit in ipending. We already check the KB_BUF_FULL bit, so there should be no races: an IRQ should have occured since there is some data, but we haven't processed it because of the spltty(). I hope that IRQs are serialized so that ones for the keyboard and the psm don't happen concurrently. Then ipending gives lots of information: ipending & kbd_IRQ && !(ipending & psm_IRQ) => scancode for keyboard !(ipending & kbd_IRQ) && ipending & psm_IRQ => scancode for psm ipending & kbd_IRQ && ipending & psm_IRQ => can't happen, we hope !(ipending & kbd_IRQ) && !(ipending & psm_IRQ) => oops, lost kbd IRQ Bruce
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