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SubjectRe: UUIDs (and devfs and major/minor numbers)
Date
In article <linux.kernel.199906170402.AAA01023@rsts-11.mit.edu>,
<tytso@mit.edu> wrote:
>
> So here we are, arguing about names, because suddenly Ted admitted
> that a virtual FS might be good. But then he says he doesn't like the
> names. Before that he was denying to the hilt that a virtual FS had
> any merit.
>
>Sigh. Let me try again. The fact that people are arguing about names
>means that it is clear the kernel should *not* be dictating what shows
>up in /dev. That should be done by a user-mode daemon. Like it or not,
>the names in /dev *are* policy, and kernel should not be dictating
>policy. Therefore, the kernel should not be deciding what names appear
>in /dev. Q.E.D.

The namespace for /dev was dictated a long time ago, and you vary
from that namespace at your own risk. (I like to number console
devices tty1...tty9, ttya...ttyf. SVGATextMode, and X11 wants to
number them tty1...tty15. Thus symlink heaven. Which feeds right
into....)

"But I don't like the devfs defaults!"

Symlinks are your friend. If you can't live without the dubious
benefit of having the kernel not tell you information, but instead
have to guess about what devices are, you can do this with symlinks.

``/dev/tty1 -> /devices/tty1'' is close to exactly the same as
``mknod /dev/tty1 c 4 1'', except for the error messages you get
when you bobble the magic. Where a devfs wins, and wins big, is
that if you choose not to place your faith in black magic, you can
actually open the device -- it's really hard to open block 4, minor
1 by itself.

>Instead, the kernel should be exporting sufficient information so that a
>user-mode daemon can provide whatever interesting naming scheme

No. The kernel should be exporting the information so that a program
can open devices with that information. The traditionalist can always
choose to poo-poo this approach and use the traditional stone axe to
open devices with.

____
david parsons \bi/ I'm amazed that people are still opposed to this.
\/

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