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

David Waite (mass@ufl.edu)
Sat, 9 Oct 1999 20:02:03 -0400


> -----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.

-David Waite

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