Subject: Re: [RFC][patch 00/12] clocksource / timekeeping rework V2
From: Daniel Walker <dwalker@fifo99.com>
To: john stultz <johnstul@us.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>, linux-kernel@vger.kernel.org,
       Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>
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Date: Thu, 30 Jul 2009 22:33:50 -0700
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On Thu, 2009-07-30 at 13:56 -0700, john stultz wrote:
> On Thu, 2009-07-30 at 11:08 -0700, Daniel Walker wrote:
> > On Thu, 2009-07-30 at 10:16 -0700, john stultz wrote:
> > > Clocksources as modules was one of the initial design goals I had way
> > > back. The benefit being that an older distro kernel could be made to
> > > support newer stranger hardware via a clocksource driver. While the
> > > hardware vendors have for the most part consolidated on HPET/ACPI PM
> > > which has mostly avoided the need, I still think its worth preserving.
> > 
> > If the PIT case is a real use case for unregister than we can keep it
> > around. If not, then that path just becomes unused and all unused code
> > is open for removal from my perspective.
> > 
> > If the case you describe above is a good one, then someone eventually
> > will add back the unregister path. Which should come with a good reason
> > and with an actual user of the code..
> 
> The case I describe above is one where the user of the code doesn't
> necessarily have the ability to add back the unregister path. 

I'm not sure I understand your example.. Your saying a situation where
the kernel can't modified and reloaded, and the hardware clocks aren't
fully implemented in code yet?

> Old distro kernels can be difficult to make changes to when new hardware
> is later released, so being able to just backport a module, compile and
> load it to get a unexpectedly strange new bit of hardware to work with
> an older distro kernel seems valuable enough to keep the code around to
> me.

You can just as easily back port the code as a built in, and reload the
kernel right? Why would it need to be a module?

Daniel

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