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    SubjectRe: devlinks: an alternative to devfs
    Michael Elizabeth Chastain writes:
    > Here is another idea: devlinks, an alternative to devfs
    > A devlink is similar to a symlink, but with the name of a device
    > driver rather than the name of another file:
    > /dev/cua1 *-> char/tty:1
    > /dev/hda *-> block/ide:0
    > A devlink has an owner, group, and permission bits, which can be
    > set in the usual way. A devlink persists across crashes and shutdowns
    > with no special work.
    > The system administrator can rename a devlink to whatever they want,
    > so FSSTAND remains a user-space convention and is not enforced by
    > the kernel. Administrators can also create devlinks wherever they
    > want, for example, inside a chroot'ed file system.
    > devlinks could also specify parameters to their drivers. For instance,
    > all of the /dev/fd* files would become devlinks like this:
    > /dev/fd0 -> block/fd:0
    > /dev/fd0D360 -> block/fd:0,format=360
    > /dev/fd0D720 -> block/fd:0,format=360

    I see a problem with this: when you open /dev/block/fd:0,format=360
    the kernel will have to parse "fd:0,format=360" in order to determine
    which set of f_ops callbacks are required for that device. And it
    looks like you would need to search all these entries too. This is
    different than implementing a devfs, since it won't use the dcache. I
    think this scheme will be rather slow.

    > Devlinks can be put anywhere the administrator wants, such as chroot
    > jails, or devlinks in /tmp during a system installation.

    You can mount devfs N times.

    > Devlinks solve the limitation of 8-bit minor numbers almost forever
    > (there is some huge limit on the length of a filename but I doubt that
    > will ever be a problem).

    Personally: "yuk" :-) Sorry.



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