Path: utzoo!attcan!uunet!lll-winken!sun-barr!cs.utexas.edu!samsung!usc!snorkelwacker!bloom-beacon!eru!luth!sunic!mcsun!inria!geocub!pelegrin From: pelegrin@geocub.greco-prog.fr Newsgroups: comp.sys.ibm.pc Subject: Re: chaining interrupts Message-ID: <1490@geocub.greco-prog.fr> Date: 17 Nov 89 08:16:31 GMT References: <4543@solo5.cs.vu.nl> <1484@geocub.greco-prog.fr> <1989Nov16.173228.7309@esegue.segue.boston.ma.us> Sender: news@geocub.greco-prog.fr Reply-To: uunet!mcsun!inria!geocub!goofi!pelegrin (Uncle Ben's) Organization: ENSERB 351 Cours de la Liberation 33405 TALENCE tel 56 84 65 00 Lines: 30 In article <1989Nov16.173228.7309@esegue.segue.boston.ma.us> johnl@esegue.segue.boston.ma.us (John R. Levine) writes: >In article <1484@geocub.greco-prog.fr> pelegrin@goofi.UUCP (Uncle Ben's) writes: >> It is absolutely harmless to link interrupt routines one to >>another WITH THE SAME INTERRUPT VECTOR provided that, for interrupts >>such as timer ticks, the total amount of time spent in the routines >>does not exceed the tick clock rate... > >Well, sometimes. The problem is that many cards were not designed with >interrupt sharing in mind and so are not good citizens about the way that >they handle their interrupt line. I have used cards (a WD8003 Ethernet, for >example) that keep anything else from interrupting on the same level. From a software point of view, if you handle chaining properly in your interrupt routine, you will be able to run it without any problems provided that you load it AFTER all interrupt routines using the same vector since, as you pointed, older-designed interrupt routines may issue a single IRET on exiting instead of properly linking to the next interrupt on the list... From a hardware point of view, I don't know... f.p. ------------------------------------------------------------------------------ ! Zeu : The craziest programmer in France ! _________ ! !---------------------------------------------! / | \ \ ! ! Francois Pellegrini is : ! / |__ ___/ \ ! ! pelegrin@goofi.greco-prog.fr ! \ | | / ! ! uunet!mcsun!inria!geocub!goofi!pelegrin ! \ | | / ! ! pelegrin@goofi.UUCP ! ! ------------------------------------------------------------------------------