Re: udev and ISA network cards

[Hannes Reinecke <hare@suse.de>]

Hi Olaf,

Olaf wrote:
> Kay Sievers wrote:
> 
>>> I would like to use ISA cards in combination with persistent net rules,
>>> especially renaming ethX to something like internal / internet / etc. as
>>> this is somewhat easier to remember ;-)
>>>
>>> Is this at all possible?
>>
>> It should work.
> 
> [... snip snip ...]
> 
>> This needs to be fixed in the kernel driver, it needs to set the
>> parent device of the netdev before it is registered.
> 
> I was afraid you were going to say something like that ...
> Ah well, I'll start staring at kernel driver code then.
> 
Which would help you only to a very limited amount.

udev relies on device autodetection, ie a (hardware) device must
have some means by which someone else can identify it.
With PCI this is no problem at all, as each device has its
vendor/device ID as per spec.

ISA OTOH is a different beast. And if you trawl memory back to
the ISA days, the main problem with it was that it _doesn't_
have an independent identifier.
IIRC you couldn't even identify the slot itself; each device
mostly hardcoded to use a specific I/O address / region and
some IRQ. And it was up to the task of the admin to ensure
each device got a separate addr/irq tuple.

Hence they invented PnP IDs which provide for exactly this
sort of identifier.

So, translated to udev this means that any ISA card providing
PnP IDs should work, or at least it should be possible to make
it work with udev.
Any ISA card _not_ providing PnP IDs you're basically out of luck.
The only choice you'd have here is to use some sort of lookup-table
which provides a static assignment between IO addresses and drivers.

HTH.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
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