Date: Tue, 12 Apr 2005 18:32:14 -0700
From: "Paul E. McKenney" <paulmck@us.ibm.com>
To: Adrian Bunk <bunk@stusta.de>
Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: 2.6.12-rc2-mm2
Message-ID: <20050413013214.GJ1367@us.ibm.com>
Reply-To: paulmck@us.ibm.com
References: <20050408030835.4941cd98.akpm@osdl.org> <20050410224834.GK4204@stusta.de> <20050411151832.GA1301@us.ibm.com> <20050413003604.GH3631@stusta.de>
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On Wed, Apr 13, 2005 at 02:36:04AM +0200, Adrian Bunk wrote:
> On Mon, Apr 11, 2005 at 08:18:32AM -0700, Paul E. McKenney wrote:
> > On Mon, Apr 11, 2005 at 12:48:34AM +0200, Adrian Bunk wrote:
> > > kernel-rcupdatec-make-the-exports-export_symbol_gpl.patch
> > > add-deprecated_for_modules.patch
> > > add-deprecated_for_modules-fix.patch
> > > deprecate-synchronize_kernel-gpl-replacement.patch
> > > deprecate-synchronize_kernel-gpl-replacement-fix.patch
> > > change-synchronize_kernel-to-_rcu-and-_sched.patch
> > > 
> > > 
> > > Please drop these patches.
> > 
> > Please keep them!
> > 
> > > Using these symbols in non-GPL modules is a legal problem at least in 
> > > the USA except for IBM,
> > 
> > Again, based on what line of reasoning?  Again, the obvious lines
> > of reasoning do not apply.
> 
> Shouldn't the IBM patents be enough reason to prevent everyone except 
> IBM from using RCU in non-GPL modules?

Not necessarily, at least according to the lawyers that I talk to.

> > >                         and all we've heard from IBM is that they are 
> > > not 100% sure that there is really no binary-only module by IBM that 
> > > might use these symbols.
> > 
> > >From my earlier message (http://lkml.org/lkml/2005/4/4/244):
> > 
> > 	Agreed, in that I know of no binary module that uses RCU.  However,
> > 	I cannot -prove- that there is no such module.
> > 
> > IOW, I am also not 100% sure that there is really no binary-only module
> > using these symbols by -anyone-, including someone -other- than IBM.
> > In addition, I know of no way that -anyone- could possibly be 100% sure
> > that there is really no binary-only module using symbols.  Hence the
> > approach of providing the year "grace period" before transitioning to
> > EXPORT_SYMBOL_GPL().
> >...
> 
> If kernel development was based on the assumption that every change that 
> might break binary-only modules would need a one year "grace period", it 
> was much different from how it's today...

This is not "every change", but a specific change, and a rather unusual
one at that.

							Thanx, Paul

> cu
> Adrian
> 
> -- 
> 
>        "Is there not promise of rain?" Ling Tan asked suddenly out
>         of the darkness. There had been need of rain for many days.
>        "Only a promise," Lao Er said.
>                                        Pearl S. Buck - Dragon Seed
> 
> 
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