Messages in this thread | | | Date | Sun, 10 Oct 1999 21:31:39 -0700 | From | "H. Peter Anvin" <> | Subject | Re: My $0.02 on devd and devfs |
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Johannes Erdfelt wrote: > > Thanks for putting forth your input into the matter. > > I'd like to here your thoughts on major/minor allocation for PnP > devices. The hypothetical example being used is connecting 1000+ modems > to a machine. (Apparentely someone has done this on an Irix machine > further solidifying the fact this can and will happen). > > Right now, it's impossible to do with the current 8/8 split of > major/minor. Some people are proposing increasing it a 16/16 split which > will significantly improve the situation, but as we've fallen into in > the past, any arbitrary limit will be broken. > > Do you think simply increasing the major/minor will solve the problem? > It seems like when you increase the major/minor space you also increase > computational complexity in determining which driver owns that > major/minor. >
Not so -- the driver is always determined by some number of left-associated bits (like an IP route); ideally it should always be the major number.
I am proposing a 32/32 split (with a 12/20 split for NFSv2), because glibc already is using a 64-bit dev_t. Adding thousands of modems therefore is not a problem, and I believe it would be very hard to construct a scenario at which this will not be sufficient for a very long time.
-hpa
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