DragonFly kernel List (threaded) for 2004-04
Re: devfs vs udev/hotplug
Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx> writes:
> : (Simon)
> :> What do people think of the udev/hotplug solution vs devfs? At first
> :> inspection, udev appears to be a little more Dragonfly-ish because of
> :> its placement in userland.
> :I'd vote for udev (or something like it)
> I think I would prefer udev over devfs. It seems silly to try to manage
> yet another fake filesystem in the kernel, just look at all the bugs
> that have cropped up in existing devfs and procfs implementations, not
> to mention unionfs and nullfs! You'd think we would have learned our
> lesson by now!
> I would definitely prefer a userland demon which performs the work based
> on what the kernels tells it to do. The kernel can still assign dynamic
> minor numbers for dynamic devices, and that is really the crux of the
> functionality we want to have.
Doesn't this sort of design imply that the kernel is instructing a daemon
to make kernel calls to service the requests? Isn't that a lot of
address space crossing or do I not understand how a userland file "server"
would work? I realize that this will be done with fast messages but such
designs leave me with "speed" doubts. This might be a bad example for when
that speed matters though.