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

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

On Thu, Mar 11, 2010 at 11:50 PM, Masao Uebayashi 
<uebayasi%gmail.com@localhost> wrote:
> On Thu, Mar 11, 2010 at 11:32 PM, Johnny Billquist <bqt%softjar.se@localhost> 
> wrote:
>> I missed when Jochen wrote this, so I'll comment now.
>> This might sound tempting, but I don't think it is a good idea.
>> Keeping track of changes and trying to retain them over reboots is
>> risky. And the mappings need to be able to handle complex things, such
>> as several names pointing to the same device. And people using totally
>> different names. So, both renames, chmod, chown, unlink and mknods needs
>> to be tracked.
>
> Yes, keeping track of state is complex.

Speaking of tracking state...  I've found that keeping track of state
in devfsd is very wrong.  It duplicates what filesystems already does.
 So what we need for emulating "traditional" view is a way to proxy
those state bits nicely (probably to tmpfs).

Speaking of persistency, I come to think it's totally *not* worth in devfs.

So users have two options:

- Traditional /dev
  - Fine grained access control
  - Persistent
    - Relying on UFS (or whatever)
  - Static configuration

- New /dev
  - Simplified access control
  - Volatile
  - Dynamic configuration

Masao