linux-kernel - Re: [PATCH] x86 APM: delete Linux kernel APM support

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Date:	Mon, 28 Mar 2011 07:18:41 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Len Brown <lenb@...nel.org>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>, x86@...nel.org,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] x86 APM: delete Linux kernel APM support

* Len Brown <lenb@...nel.org> wrote:

> > .42 removal might be too fast, considering the typical release schedule of 
> > Linux distributions. And i'm still doubting the removal itself: we are 
> > adding lots of special-purpose subarch drivers to arch/x86/ as we speak 
> > (the embedded mess coming to x86) - which drivers will be tomorrow's APM 
> > code. On what grounds do we treat APM support differently?
> >
> > Our general compatibility with old hardware is an *asset* that we should value.
> 
> My guess is that the customers have died off,

How do we know that? Users are on a bell curve, with a fat tail. If stuff just 
works - and that's not unexpected from relatively simple (and most likely to be 
used) APM functionality like APM-poweroff, why should they ever report 
problems?

Removing a driver based on lack of visible feedback is like removing 190,000 
apps from a 200,000 apps app store, on the (valid) observation that the top 
1000 apps receive 99% of the traffic and use so the remaining 1% are just a 
maintenance burden.

There's value in the concept of knowing that we do not do forced obscolescence 
in Linux and there's a value in a very broad "there's a driver for that" 
concept, just like there's value in a very broad "there's an app for that" 
concept.

> and so the code is no longer an asset, but a maintenance liability.
> 
> If there is a buzzing community of people running 2011
> linux kernels on their ancient laptops in APM mode,
> then the APM maintainer would probably know about them.

Not if most of them use APM-poweroff. I think i even had a desktop box (not a 
laptop) that supported APM suspend (or am i mistaken there, was APM suspend 
support only limited to laptops?).

Thanks,

	Ingo
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