Subject: Re: [PATCH] sky2: irqname based on pci address

From: Stephen Hemminger <[email-masked]>
Date: Thu, 1 Oct 2009 10:14:50 -0700

On Thu, 1 Oct 2009 10:11:46 -0700
Stephen Hemminger <[email-masked]> wrote:

> This is based on Michal Schmidt fix for skge.
> 
> Most network drivers request their IRQ when the interface is activated.
> sky2 does it in ->probe() instead, because it can work with two-port
> cards where the two net_devices use the same IRQ. This works fine most
> of the time, except in some situations when the interface gets renamed.
> Consider this example:
> 
> 1. modprobe sky2
>    The card is detected as eth0 and requests IRQ 17. Directory
>    /proc/irq/17/eth0 is created.
> 2. There is an udev rule which says this interface should be called
>    eth1, so udev renames eth0 -> eth1.
> 3. modprobe 8139too
>    The Realtek card is detected as eth0. It will be using IRQ 17 too.
> 4. ip link set eth0 up
>    Now 8139too requests IRQ 17.

One other note, the issue is less of a problem for most usage of sky2
because the drive is used mostly on systems that support MSI interrupts
which can never be shared.