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    SubjectRe: UUIDs (and devfs and major/minor numbers) writes:
    > Explain to me how this is different from mounting devfs onto /kernel
    > and using devfsd to populate a disc-based /dev.
    > It isn't, as long as the names given by devfs are specific enough that a
    > user-mode daemon knows what the device is. So if devfs is creating
    > names like sda1, or c0t0d0s4, this isn't useful. Names like:
    > /kernel/devices/pci/adapecc2980_0/... aren't something you'd *want* to
    > appear in /dev, and indeed they don't appear in /dev under Solaris.

    I don't see how a hardware-based name like
    /kernel/devices/pci/adapecc2980_0/... is any better than one that
    includes the host#, bus# and so on.

    > But this is a straw-man argument, because it ignores the persistence
    > problem with a dynamic disc-based /dev which is managed with a user
    > space daemon. This is a problem that's been overlooked.
    > Consider what happens if your daemon creates and deletes device
    > entries based on information from the kernel as to what devices are
    > installed (and drivers loaded). When a new device is plugged in, *what
    > permissions should be given*? OK, say you get some default. So the
    > sysadmin does chmod(1) to change this.
    > What happens if a device is removed? The daemon deletes the device
    > entry. Then the device is plugged back in again. *What permissions
    > will be given*?
    > What makes you think the daemon should delete the device entry? I
    > wouldn't. I would keep it there, since the device entry is cheap,
    > and most of the time when a device is removed it's likely to come
    > back later. In the rare case where hardware is being physically
    > removed and it will never come back, the system administrator can
    > simply delete the device for good later.

    I'd want it removed, since it's clutter if there hardware isn't there.

    > Again I'll ask the question I've already asked a number of times. How
    > would you cleanly support a construct like this:
    > opendir ("/dev/ide/cd");
    > loop;
    > 1) I don't think this is useful.

    Yes it is.



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