Re: devfs - why not ?

From: Horst von Brand (vonbrand@sleipnir.valparaiso.cl)
Date: Wed Apr 12 2000 - 20:25:38 EST


Ricky Beam <jfbeam@bluetopia.net> said:

[...]

> If you wanted to be a purist, modules need a new function for reporting
> devfs information... init_module, delete_module(?), devfs_module? That
> certainly fixes one problem (and kills the need for devfsd.)

No. How do you load a module for /dev/foo117, when /dev/foo117 doesn't
currently exist? The kernel shouldn't have to know about each and every
device that might some day show up as a driver module (even third-party,
binary-only compiled after the kernel proper perhaps). This mandates some
userland involvement, with some configuration file that tells the daemon
what to do in each case. This is elegantly solved in the traditional case
with just a device file created before use, major/minor (more generally,
device id) tell the kernel what module to ask for. You can then also
painlessly set (and preserve) permissions on the device in the filessytem.
Cost is one inode on disk per device.

The whole devfs idea more and more looks like ballast to me.

-- 
Horst von Brand                             vonbrand@sleipnir.valparaiso.cl
Casilla 9G, Viņa del Mar, Chile                               +56 32 672616

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