Date: Sat, 26 Dec 1998 23:43:06 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: zhihuizhang <bf20761@binghamton.edu> Cc: hackers <freebsd-hackers@FreeBSD.ORG> Subject: Re: Questions about interrupt handling Message-ID: <199812270743.XAA42331@apollo.backplane.com> References: <Pine.SOL.L3.93.981226220445.11330A-100000@bingsun2>
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:Hi, : :I know that FreeBSD handles interrupts on a software basis which means :that we do not mask any interrupt off in 8259. I am just wondering if a :certain interrupt is masked off in 8259 or it does not get serviced quick :enough, what will the device controller (such as disk controller) respond? :Will it re-issue the interrupt or just give up? Or will it NOT generate :another interrupt until the previous one has been serviced? Maybe :different device controllers behave differently. : :Thanks for any help. : :-------------------------------------------------- :| Zhihui Zhang, http://cs.binghamton.edu/~zzhang | On Intel machines, virtually all interrupts are edge triggered. They occur once and the system must 'remember' them if it can't deal with them instantly. The hardware interrupt is not reissued. One of the oddest problems with Intel boxes is the keyboard interrupt. If you loose the interrupt, the controller can get into a state where it doesn't issue another interrupt every again. The code required to deal with this is messy but there isn't much we can do about it -- it's the hardware that is screwing up. -Matt Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet Communications & God knows what else. <dillon@backplane.com> (Please include original email in any response) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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