Re: [2.1.65] New patch for serial port IRQ setup.

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 24 Nov 1997 11:27:20 +0000 (GMT)

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> > You cannot share ISA interrupts between two standard seperate ISA cards
> > in general. The way the cards are wired means that whoever has the strongest
> > drivers sets the interrupt level.
> >
> With CONFIG_SERIAL_SHARE_IRQ defined it seems that my mouse and modem can
> share interrupt under X. It slows both down, but it's stable.

See "in general". The problem occurs if you have two typical ISA boards. Neither
tristates the irq line. Thats why Linux (and other OS's tend to lock one if
you go for the other). On PCI this sort of stuff is done right but modems
appear to be going USB rather than PCI card

Alan

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