From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Greg KH <greg@kroah.com>
Subject: Removing sysdevs? (was: Re: Is sysfs the right place to get cache and CPU topology info?)
Date: Wed, 2 Jul 2008 23:41:44 +0200
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Cc: Andi Kleen <andi@firstfloor.org>, Nathan Lynch <ntl@pobox.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Paul Mackerras <paulus@samba.org>, torvalds@linux-foundation.org,
       linux-kernel@vger.kernel.org
References: <18539.8141.683072.967851@cargo.ozlabs.ibm.com> <486B9B3A.4060709@firstfloor.org> <20080702185145.GB20938@kroah.com>
In-Reply-To: <20080702185145.GB20938@kroah.com>
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On Wednesday, 2 of July 2008, Greg KH wrote:
> On Wed, Jul 02, 2008 at 05:14:02PM +0200, Andi Kleen wrote:
> > Nathan Lynch wrote:
> > > Andi Kleen wrote:
> > >> Andrew Morton <akpm@linux-foundation.org> writes:
> > >>> sysfs is part of the kernel ABI.  We should design our interfaces there
> > >>> as carefully as we design any others.
> > >> The basic problem is that sysfs exports an internal kernel object model
> > >> and these tend to change. To really make it stable would require 
> > >> splitting it into internal and presented interface.
> > > 
> > > True, but... /sys/devices/system/cpu has been there since around 2.6.5
> > > iirc.  A google code search for that path shows plenty of programs
> > > (including hal) that hard-code it.  Exposed object model or not,
> > > changing that path would break lots of software.
> > 
> > Yes it would.
> > 
> > But Greg is making noises of getting rid of sysdevs and it wouldn't
> > surprise me if that ended up being user visible since most object
> > model changes end up being visible.
> 
> I hope to make sysdevs go away in such a manner that the sysfs tree does
> not change at all.  That's my goal, but we still have a long ways to go
> before we can even consider attempting to do this, so don't worry about
> putting things in this location if you feel it is the best fit.

Speaking of which, I'm very interested in the removing of sysdevs, since they
don't fit into the new suspend/hibernation framework I'm working on.  Can you
please tell me what the plan is?

Thanks,
Rafael
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