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Message-ID: <3efb10970702061043m43f5b3eelfa24fbb95721acb4@mail.gmail.com>
Date: Tue, 6 Feb 2007 19:43:47 +0100
From: "Remy Bohmer" <l.pinguin@gmail.com>
Reply-To: linux@bohmer.net
To: j-almeida@criticalsoftware.com
Subject: Re: IRQ Sharing
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <200702061801.58465.j-almeida@criticalsoftware.com>
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Hello Jorge,

It is not uncommon that interrupt lines are hardwired to each other on
a standard PC-board.
Therefor it is not always feasible to get rid of interrupt sharing.
Especially on-board USB adapters can easily use up to 5 interrupt
lines on a standard main-board. Also, sharing of interrupt lines (by
hardwiring them) between on-board devices and PCI slots is also common
practice.

The PCI specification explicitly states that PCI devices can share
interrupt lines, and that your drivers must be capable of handling
this.

Why is sharing a problem for you?

If you do not have special realtime requirements, it usually should be
no problem...


Remy


2007/2/6, Jorge Almeida <j-almeida@criticalsoftware.com>:
>
> Hello to all.
>
> I'm running an application that uses several IO boards in a PCI bus.
>
> My main problem is the virtual IRQ sharing between several boards.
> I mean for example:
>         1 ethernet board IRQ = 169;
>         1 ADC card IRQ         = 169;
>
> I want to get ride of this behaviour, and changing the slot position of each
> board is not enought, to get something like (for example):
>         1 ethernet board IRQ = 169;
>         1 ADC card IRQ         = 170;
>
> Where in the kernel i can see the algorithms for the APIC system where the
> virtual IRQs are distributed? Or exist already any patch that permits to
> solve my problem?
>
> I'm using kernel 2.6.16.27, in a single machine with Intel pentium IV
> processor and chipset ICH4.
>
> Thanks for any reply.
> Greetings.
>
> --
> Jorge Almeida
> j-almeida@criticalsoftware.com
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