Messages in this thread | | | Date | Fri, 02 Jan 2004 03:53:56 +0000 | From | Tyler Hall <> | Subject | Re: udev and devfs - The final word |
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Since we're moving toward treating device numbers as unique handles for devices in a system, why can't we just dynamically allocate them like process ID's? As each device driver loads and registers with the kernel, it can request a device number and the kernel can assign the next available one.
Tyler
Rob wrote:
>On Wednesday 31 December 2003 07:31 pm, Rob Love wrote: > ><snip> > > >>This is definitely an interesting problem space. >> >>I agree wrt just inventing consecutive numbers. If there was a nice way >>to trivially generate a random and unique number from some >>device-inherent information, that would be nice. >> >> Rob Love >> >> > >my first thought was hardware serial numbers, but i'm guessing they mostly >don't exist based on the discomfort caused by the pentium 3 serial number in >the past. my second thought was raw latency. in the real world, 2 identical >devices of any nature are going to respond electrically at different rates. i >kind of stole the concept from what i read about the i810 rng... quantum >differences can distinguish between 2 of anything, and based on the response >time, 'cookies' can be written out to keep them separately ID'd. some devices >will get slower over time, e.g. increasing error rates and aging silicon will >throw the 'cookie' off, so you'd re-calibrate every so often, like on a >reboot. those are rare for some of us ;) > >the big IF: can you measure that with enough precision to at least decrease >the probablity of collision? > > >
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