Re: [RFC] New Driver Model for 2.5

Linus Torvalds
2001-10-24T22:44:44Z

On Wed, 24 Oct 2001, Alan Cox wrote:
>
> I don't think it is a big problem. We can add virtual nodes. They way I
> see it we either
> a) put in grungy subsystem hacks
> b) register virtual device nodes for subsystems when needed
>
> b feels cleaner

I agree. I would personally see us using _more_ "virtual device node"
things already: right now we have things like SuperIO chips that contain
both a serial line and a parallel port (and...), and some drivers do
really ugly things with them - keep them as one "struct pci_dev", and then
have two drivers sharing the device.

It would be much cleaner to have _one_ driver for such SuperIO chips (a
"multinode" driver), which just creates two virtual pci_dev structures,
and lets the regular serial driver handle the "virtual serial device" etc.

That has the advantage of:
- not needing special hacks in various serial/parallel drivers
- the devices show up naturally and logically in whatever user mode
"device m nager" tree

So the device nodes do not have to match the physical tree. The physical
device tree only sets up the initial physical scanning, and obviously
limits _reality_ ;)

Linus