Re: UUIDs (and devfs and major/minor numbers)

H. Peter Anvin (hpa@transmeta.com)
Fri, 18 Jun 1999 02:27:40 -0700


Paul Jakma wrote:
>
> > a devmgr without kernel interaction would be a complicated, gross
> hack.
> > How would you handle dynamic devices with your devmgr? poll every
> second
> > for new devices? and what do you poll? Your devmgr has to get the
> > information about new/expired devices from somewhere - so the kernel
> has
> > to export this information somewhere. Why not in the most logical
> way:
> > directly to /dev?
>
> Trivially: it's the module installer's job. (Actually, dynamic devices
> are bad, this one of the major reasons why.)
>
> -hpa
>
> who said anything about modules? ok, you might be able to hack something
> up with the module installer, ugly.. but anyway.
>
> Now what do you about dynamic devices handled by the same driver: eg
> hot-plug buses like usb, firewire?? Do you propose that the complete
> driver module should have to be loaded/unloaded every time the user
> (un)plugs a device onto/off the bus?

Absolutely. PCMCIA has done that for years.

> If that's how you want to do things, then i can see why you think
> dynamic devices are bad, or at the very least ugly.

"dynamic devices" means something different in the Linux universe than
"hotpluggable devices." "dynamic devices" are those whose device
numbers move around.

> Better to reboot your computer or unload/load the bus driver whenever
> you want to plug in, eg, your firewire digital camera, or your usb
> speakers. Yes, much better. (sorry for the sarcasm).
>
> On the otherhand, with devfs, dynamic devices become piss easy. You plug
> in your USB camera. The USB driver registers it, and the /dev entry
> magically appears. (what it'll be called is another issue - not
> devfs's). A lot less pain, a lot cleaner, a lot saner, and generic.

-- 
"The user's computer downloads the ActiveX code and simulates a 'Blue
Screen' crash, a generally benign event most users are familiar with
and that would not necessarily arouse suspicions."
-- Security exploit description on http://www.zks.net/p3/how.asp

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