[ltp] Re: Generic battery interface

Vojtech Pavlik linux-thinkpad@linux-thinkpad.org
Sat, 29 Jul 2006 15:42:25 +0200


On Sat, Jul 29, 2006 at 03:51:45PM +0300, Shem Multinymous wrote:

> >IMO the right way here would be to have a nice GUI for configuring udev
> >included with the distro, that'd let you browse the sysfs tree and
> >point'n'click to create the rule you need.
> 
> That's still an extra level of indirection. You have to use the nice
> GUI to create a new /dev/something, and then point your at at dev
> /dev/something. And you have to be root to do that, whereas some sysfs
> stuff is world-readable.

If that app opens /dev/something by default, which is usually the case,
there is only one step.

> >The reason behind this was to force people NOT use sysfs directly when
> >interfacing to the OS. ;)
> >
> >Because sysfs wasn't intended to be an API you can rely on, one that's
> >fixed in stone and cannot be changed for compatibility reasons. I
> >believe it failed in that respect.
> 
> Is sysfs supposed to be a private" API that only "special services
> services" look at? It has definitely failed in this respect -- It's
> just too convenient and attractive. I'm not sure that's a bad thing...

I believe it was originally intended as a cleaner replacement for procfs
- to allow the kernel export information about itself in a clean, safe,
and consistent way. It wasn't intended for data delivery. 

I don't know whether the current state of things is good or bad.

> Given the current usage pattern of sysfs, is it still a bad idea for
> it to carry device inodes?
 
That remains an open question.

-- 
Vojtech Pavlik
Director SuSE Labs