Re: new version of udev has different cd/dvd devices

[Darren Salt <linux@youmustbejoking.demon.co.uk>]

I demand that Kay Sievers may or may not have written...

> On Fri, Dec 30, 2005 at 07:09:20PM +0100, Marco d'Itri wrote:
>> On Dec 30, Greg KH <greg@kroah.com> wrote:
>>> Or we can just stick with the rules we have today that use %e just fine,
>>> as it emulates exactly what a static /dev would have done, and no one is
>>> complaining about it :)
>> People are complaining about it because events are not received in bus
>> order anymore, so the names randomly change (and since there is no locking
>> often the same links is created for two devices).

> Exactly. That's the reason why it will be removed.

So, basically, you're removing something which *worked* here because of an
unrelated change which broke it.

>> But still, I'd rather keep it as long as possible since half broken is
>> better than totally broken and I do not have a replacement ready.

> That doesn't makes sense. %e it conceptually completely broken and offering
> something that can't work does not give any value.

Can you provide instances in which it *doesn't* work, given events received
in bus order?

> Just get rid of _any_ simple enumeration, for exactly the same reason a
> kernel devfs is completely useless.

I don't think so - AFAIK, use of "%e" doesn't cause processes to hang due to
implementation bugs. (And that is, AIUI, exactly why the kernel devfs is
useless.)

> Write out a rule at discovery (from udev itself) for every unconfigured
> device and you get a sane enumeration, that will not change at next boot.

ITYM "sane enumeration that will not change".

If, with no devices previously configured, it differs from what would be done
with events sorted into bus order, I for one will consider it broken for the
simple reason that it cannot be predicted from bus order.

What about device removal? What about swapping devices due to (for example)
interrupt problems? What about plugging the same (hot-pluggable) device into
a different port?

[snip]
> Writing out rules is reliable, predictable and one can understand what's
> going on.

I'd say exactly that about %e and module probing, as was before the event
order was randomised.

> The %e is unfixable and will definitely die some day.

Right now, to me, it looks fixable.

-- 
| Darren Salt | d youmustbejoking,demon,co,uk | nr. Ashington,
| Debian,     | s zap,tartarus,org            | Northumberland
| RISC OS     | @                             | Toon Army
|   Let's keep the pound sterling

..and the great tagline hunter crouches silently, text editor at the ready..


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