Re: [PATCH] fix udevtrigger first/default/last ordering

[Greg KH <greg@kroah.com>]

On Thu, Apr 13, 2006 at 02:22:49AM +0300, juuso.alasuutari@tamperelainen.org wrote:
> Quoting Kay Sievers <kay.sievers@vrfy.org>:
> 
> > On Sat, Apr 08, 2006 at 05:51:57PM +0200, Thomas de Grenier de Latour wrote:
> > > There is some logic in udevtrigger (udev-0.89 or current git) to make
> > > some events being triggered first or last. But it doesn't work because,
> > > in device_list_insert(), some "sysfs_path"-prefixed devices paths are
> > > compared to some unprefixed paths
> >
> > Fixed. Thanks a lot,
> > Kay
> 
> I don't completely understand the issue that this patch deals with, but does it
> have something to do with module loading order? This has been giving
> considerable trouble for people (also previously discussed on this list), and
> is still one major obstacle for udev to reliably replace hotplug. At least this
> is the case for the distribution I assist in developing.

It is?  What distro?

> Is there a chance that udev could in the future load modules (network, audio,
> etc.) in the same order every time if no significant hardware changes take
> place? If yes, when and thanks to what changes? If not, what prevents it?

No, as the modules could be loaded in any order if the buses are probed
a little bit differently next boot time.  Or if the BIOS reorders the
bus numbers.  Or another PCI device is added to the system.  Or one
removed.  Or any of a zillion different other things happening.

In short, any reliance on the order of modules being loaded, in order to
name devices properly for a system is broken.  Use persistant names,
that is what udev is for.  Look at /dev/disk/ for examples of how to do
this with block devices today.  It works wonderfully thanks to Kay's
work.

thanks,

greg k-h


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