Re: DOS PCI and Interrupts

["Peter Marek" <peter.marek@marekmicro.de>]

Hi,

1) you will have to chain the interrupt
2) To install your ISR, save the "old" Interrupt vector from the interrupt
vector and replace it with yours.
3) anytime you get the interrupt you need to check if your card issued the
IRQ.
4) at the end of your ISR you need to call the "old" interrupt vector. Do
not issue a iret instruction.
5) At system start, the BIOS assigns default interrupt vectors which point
to a simple iret instruction. So, in case no other driver has been installed
before your driver, the default vector will generate the iret instruction
for you.

Regards,

Peter Marek
General Director
MarekMicro GmbH
tel.: 049-9621-9732-110
fax: 049-9621-9732-199
www.marekmicro.de

----- Original Message -----
From: "Mike Berkowitz" <mberkowitz@Futurex.com>
To: <pci-sig@znyx.com>
Sent: Thursday, May 30, 2002 2:03 AM
Subject: DOS PCI and Interrupts


> Hello all,
>
> I am developing a DOS based PCI device driver for a communications card. I
> am a little confused as to how to handle the interrupt. Since PCI
interrupts
> may be shared, how do I get my ISR to work properly?
>
> Do I need to chain the interrupt?
>
> Since PCI interrupts are level triggered, how will I know if there is
> another device driver for a different device that is also sharing the
> interrupt?
>
> Any help will be greatly appreciated.
>
> Best regards,
>
> Michael H. Berkowitz
> Senior Systems Engineer
> Jones Futurex, Inc.
> 3715 Atherton Road
> Suite 1000
> Rocklin, CA 95765
> (916) 632-9450 x1340
> (916) 632-9456
> mberkowitz@futurex.com
> www.futurex.com