Re: UUIDs (and devfs and major/minor numbers)
Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 18 Jun 1999 11:40:48 +0100 (BST)
> > 2. The kernel builds a /dev
> >
> > #2 is devfs
> > #1 is devfs with a script walking it.
> >
> > You can actually rip out chunks of devfs for #2 but the hooks you need to build
> > the information database happen to be exactly the ones you need for a full
> > devfs
> >
> The problem is that neither the kernel nor user space have the full
> information; and I would argue that more of the information is in user
> space than in kernel space. Look at what PCMCIA does: not only does it
> build /dev in user space, but it also manages kernel modules. I would
> hate so see modprobe in the kernel, which would have been one way to
> implement kmod.
Which is why you need to export the kernel device view in some format to the
user space. Either as a file system or a binary table of some form. The
only place the kernel side information lives is in the drivers, so they need
to provide information back to whatever exports data to user space.
Thats absolutely identical to the devfs hooks. devfs is generating an fs
from them, doing a usermode smart /dev is exporting the same data devfs
builds on into user space and doing the hard thinking in user space.
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