Re: [linux-usb] Re: USB device allocation (fwd)
Johannes Erdfelt (jerdfelt@sventech.com)
Wed, 6 Oct 1999 19:03:44 -0400
On Wed, Oct 06, 1999, Matthew Dharm <mdharm@one-eyed-alien.net> wrote:
> On Wed, 6 Oct 1999, David Waite wrote:
>
> > A number of problems though:
> > 1. People will need to realize that they are not guaranteed that usb0 will
> > remain usb0. If someone unplugs a hub off root with 126 devices tied to it,
> > they will probably all get scrambled. So in the end, you need some way to
> > make sure that if you want a certain device, you are going to get it. A
> > Lookup-then-Check method will work, if it repeats on failure.
>
> The point is that nobody will directly access usb0 unless they know what
> they're doing. People will generally use the symlink for the device.
> Also, since the assignment will always roll upwards (like process IDs), if
> usb0 is disconnected and a new device connected, the only way that the new
> device will get usb0 is if _all_ other usb minor numbers are assigned.
> That's a lot of devices, and one very paranoid case. If you have 255
> devices (254 attached at any one time), then you know you should be
> careful.
This sounds like an interesting solution, but I have some questions. How
would you merge the 2 sets of ioctl's for the device.
There's the set of ioctl's for the USB specific portion of it, then
there's the set of ioctl's for the deriver specific (lp, scsi, etc).
AFAICT, this isn't going to be easy with the current setup.
JE
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