Date: Mon, 15 May 1995 07:30:12 +1000 From: Bruce Evans <bde@zeta.org.au> To: graichen@sirius.physik.fu-berlin.de, wpaul@skynet.ctr.columbia.edu Cc: hackers@FreeBSD.org Subject: Re: shared IRQ for 2nd IDE controller Message-ID: <199505142130.HAA05490@godzilla.zeta.org.au>
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>> is it supported under FreeBSD to use 2 IDE controller cards at the same IRQ >> (14) and at different port adresses - i ask because i get an "not probed due No. >> to IRQ conflict ..." - if i try it - this way it would be very easy to add >> more than 2 IDE disks to a system (i don't want to discuss the performance of >> that) - nearly all no name ide-controller cards allow to select the secondary >> port but not to use IRQ 15 for instance Multplexing the IRQ would further reduce the performance :-). >I'm pretty sure it doesn't work with FreeBSD yet. You'd have to declare >the second controller as being in conflict with the first in your kernel >config file, for one thing. But even if you did this, it wouldn't >work: the driver would likely spit out lots of timeout errors. I'll You'd probably declare the IRQ only for the first controller and somehow tell the driver to use the same IRQ for the second controller. The driver would have to enable the IRQ for only one controller at a time and handle spurious interrupts if the IRQ floats high while it is not driven by either controller. The controller that isn't driving the IRQ would have to be polled. This would increase latency. Bruce
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