Re: (Semi-random) thoughts on device tree structure and devfs

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

On Sun, Mar 07, 2010 at 06:43:49PM +0900, Masao Uebayashi wrote:
> Where component devices are symlinks to the real instances
> 
>       /dev/pseudobus0/raid0/component0
>       -> /dev/mainbus/pci0/ppb0/piixide0/atabus0/wd1/disk0/diskpart0

I already pointed this out on port-i386@, but theoretically this sounds like
a good thing for the ACPI side of things where "pseudo" (ACPI) devices need
to be matched with "real" devices.

As an example: one thing that holds back the ACPI CPU code I am working on
is that I need to be sure that e.g. cpu3 that attaches to acpi0 is the same
cpu3 that has attached to mainbus0. So:

        /dev/acpi0/cpu3
        -> /dev/mainbus0/cpu3

No idea how this works in practice (frankly, I find autoconfiguration scary).

- Jukka.

PS. Another example is the Grégoire Sutre's work with ACPI display devices;

  http://mail-index.netbsd.org/tech-kern/2010/01/20/msg006983.html