Date: Thu, 22 Feb 1996 20:55:15 +1100 From: Bruce Evans <bde@zeta.org.au> To: freebsd-hackers@freebsd.org, koshy@india.hp.com Subject: Re: ISA device irq/mem auto-configuration Message-ID: <199602220955.UAA03013@godzilla.zeta.org.au>
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>Consider a network card : If the kernel has been configured for say, >IRQ 5 but the actual board was detected at IRQ 11, whats the right thing to >do? We could : >(a) Ignore the board : this can be pretty frustrating to the user. >(b) Print out some informative message : stating something like > "board setup for IRQ XX but kernel was configured for YY" and leave > it at that. >(c) Take in the new IRQ setting somehow and do the right thing. >Option (C) seems to me to be the right thing from the users point of >view; I don't know enough of the FreeBSD kernel to tell if it is feasible. Option (B) is right because if the user wanted the irq to be auto-detected then they would have specified this in the configuration. >I have seen in some places "-1" being used as a kind of "wildcard" address >in some drivers. Is this a convention? The wildcard for irqs is actually 0. This is standard. "irq ?" in the config file translates to id_irq == 0 in the isa device table. Unfortunately, and unspecified "irq" in the config file also translates to id_irq == 0 in the isa device table. The ambiguity isn't much of a problem in practice because there are few device [driver]s that support both auto irqs and not using an irq at all. Bruce
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