Re: DevFS vs. normal /dev (was DEVFSv50 and /dev/fb? (or /dev/fb/? ???))
Shawn Leas (sleas@ixion.honeywell.com)
Mon, 10 Aug 1998 20:55:56 -0500 (CDT)
On Mon, 10 Aug 1998, Erik Andersen wrote:
> 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.
> > --
> > Dr. Horst H. von Brand mailto:vonbrand@inf.utfsm.cl
> > Departamento de Informatica Fono: +56 32 654431
> > Universidad Tecnica Federico Santa Maria +56 32 654239
> > Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513
> >
>
> 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.
> 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
Well, if you try to acces any node inside /dev/floppy, I think the way it
works is it sends the name of the dir-heirarchy (minus /dev) to kmod.
Meaning, it would say, load "floppy".
Richard had an example of the ide-cd. DevFS would send "ide/cd" to kmod,
and if you had aliased ide-cd to ide/cd in /etc/conf.modules, it would
automagically load the ide-cd module.
> 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.
> Of course, it doesn't do this now.
Ought to ask Richard on this...
-Shawn
<=========== America Held Hostage ===========>
Day 2028 for the poor and the middle class.
Day 2047 for the rich and the dead.
894 days remaining in the Raw Deal.
<============================================>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.altern.org/andrebalsa/doc/lkml-faq.html