Re: DEVFSv50 and /dev/fb? (or /dev/fb/? ???)
Richard Gooch (Richard.Gooch@atnf.CSIRO.AU)
Sun, 9 Aug 1998 12:02:58 +1000
Alan Cox writes:
> > > Dev_fs breaks completely under such circumstances you mean. Firewire and USB
> > > need potentially quite a lot of nonvolatile state storing. For that they need
> > > a daemon if they have a daemon they don't need devfs
> >
> > What state are you referring to? The permissions? And how many device
> > nodes are you talking about?
>
> Well for USB you have to remember the state of every device plugged
> into the system on a permanent basis. Not only is this needed for
> things like hot plugging when a device loses its settings as you
> move it between ports but also to ensure that when you plug it back
> in it keeps its old configuration from last use on this machine.
>
> The amount of state per device isnt really bounded, although I would
> expect it to be small. The point I was making is you do this by
> having a usb daemon sitting around getting "someone plugged this USB
> device in, its serial id is blah, its address is xyz and its a
> camera" and taking action in user space accordingly
>
> Policy in user space
>
> The pcmcia services also use this technique.
>
> So it doesnt matter if you are using devfs or not - the daemon will
> be making the device files in either and firing things up as
> needed. It has more to fire up than just devices though - insert a
> mouse - perhaps that loads gpm ?
OK, this sounds like it will be handled nicely by the devfsd I
mentioned earlier. When a driver registers a new device entry, the
daemon is notified. It can then do whatever it requires.
Regards,
Richard....
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