linux-kernel - Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works

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Message-ID: <20110331092721.GA16570@elte.hu>
Date:	Thu, 31 Mar 2011 11:27:21 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Len Brown <lenb@...nel.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	Len Brown <len.brown@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag


* Alan Cox <alan@...rguk.ukuu.org.uk> wrote:

> > Do we know whether a distro adds this to the boot line? Do we know about users 
> > relying on it.
> 
> I certainly had hardware that needed it. Don't any more but this is more
> trying to rip out stuff without letting nature take its course.
> 
> It's a trivial feature item.

Yes.

> > > Do we really need both?
> > 
> > Probably not, as i said i do not disagree - i just think it should be more 
> > explicit. Make it a: "users of CPU models X beware" commit title, not 'remove 
> > inactive code' ...
> 
> Just make the one config variable respond to both boot configuration
> options. The parser is __init code anyway so discarded so the actual code
> cost of compatibility is exactly NIL.

Yeah, agreed.

Btw., we used to auto-detect broken HLT systems IIRC - but that got lost 
already. We should at least honor the boot parameter.

Thanks,

	Ingo
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