> Conventional
> wisdom would be that irq sharing is the surest way to a crash in a pc.
 
Some would argue that conventional wisdom is that interrupt sharing
works just fine ... and indeed it often does ... with a modern operating
system (unlike DOS) that is designed for it.  On the other hand, DOS
experience is what says that it is sure to crash a PC.

PCI interrupts are open-drain and level-sensitive, which means there
is no electrical problem sharing interrupts.  Since each PCI slot has
four interrupts, sharing is a virtual necessity.

The catch is that interrupt drivers must be written to support interrupt
sharing.  They do this by first checking to see whether the physical
device they support, needs to be serviced (i.e., whether it was the one
that signalled the interrupt), and then passing control on to the next
interrupt driver in the chain.  It's all supposed to work, and indeed it
does work when all the players play by the rules, which I think is
most of the time with newer versions of Windows, and Linux.

Sorry this probably doesn't help.

Andy



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Author: Ingraham, Andrew
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