Linux-kernel mailing list archive 1999-41,: RE: [linux-usb] Re: USB Device Allocation: Let's keep on track!

# RE: [linux-usb] Re: USB Device Allocation: Let's keep on track!

Matthias Weingart (matthias@pentax.boerde.de)
Sun, 10 Oct 1999 11:46:06 +0200 (MEST)

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On Sat, 9 Oct 1999, David Waite wrote:

> > -----Original Message-----
> > From: Theodore Y. Ts'o [mailto:tytso@mit.edu]
> > Sent: Saturday, October 09, 1999 7:50 PM
> <snipped important message about needing a devfs alternative, at least for
> now>
>
> > What we need is a way to deal with allocation major/minor
> > numbers to USB
> > devices in a sensible way, without devfs[d]. As I see it, there are 2
> > options on the table:
> >
> > 1) Allocate 1 (or more) major, and group the minors into pools based on
> > device type. i.e. 16 minors for printers, 16 minors for ACM, etc.
> > 2) Allocate 1 (or more) major, and use all of the minors as a
> > pool for all
> > devices
> >
> > May I suggest another solution, which may be work out better? If you
> > assume the use of a user-space daemon (which both of the above solutions
> > require), have the kernel USB code allocate the major numbers
> > dynamically, and let the user-mode daemon get the major number(s) out of
> > /proc/devices as necessary. This avoids the problem you mentioned about
> > not liking the kernel to tie up extra major numbers just to accomodate
> > those rare systems with 800 USB devices.
>
> I like number #2 with your dynamic allocation of major (But then again, this
> is what I would like anyways, for all devices, not just USB ;-)). So now we
> need
> to quickly decide if this is best, and then move on to making sure all the
> issues/races are hammered out, and implementation.

Why thinking about rare machines with 800 USB devices? The way described
above is only for the (short?) time we do not have devfs. Users with more
than 500 devices should wait for kernel 2.5 with devfs! The future linux
should not work with major/minors (for usb and other hotpluggable devs) it
should use something like devfs.

Matthias

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