Re: DevFS vs. normal /dev (was DEVFSv50 and /dev/fb? (or /dev/fb/?

Richard Gooch (Richard.Gooch@atnf.CSIRO.AU)
Tue, 11 Aug 1998 16:28:50 +1000


Erik Andersen writes:
>
> On Mon, 10 Aug 1998, Horst von Brand wrote:
>
> > How do you reference, say, /dev/fd0 if the floppy module isn't even loaded?
> > You need to do that so kmod loads the module, as things stand now.
>
> This is an issue I raised the other day. Currently, to enable dynamic
> device loading, you must use the magic tar stuff to create the device
> in advance with the correct permissions owner, and group. There is
> a fundamental "chicken and the egg" problem with the auto-creation
> of device special nodes and use of kmod to auto-load modules.

This isn't correct. If you attempt to do an inode lookup for an inode
that doesn't exist yet, devfs will send the name of the file to kmod
which will then load the module.
All that is required is the right alises in /etc/modules.conf

> Now in _theory_ Devfs could intercept any query for the existance
> of a device special file to then use a daemon to automagically create
> device special files with the right permissions owner, and group,
> and then if the permissions are correct, tell kmod to load the
> module. Then if it doesn't work, you get the same behavior as now
> when a device isn't supported by the kernel. And in theory, Devfs
> could then, when the last reference to a particular device special
> file is closed, tell the user space daemon to blow away the file.

None of this is needed. With a properly configured /etc/modules.conf
it all sorts itself out.

Regards,

Richard....

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