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Date: Tue, 13 Jan 2009 15:52:11 -0800
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: Jiri Kosina <jkosina@suse.cz>
CC: Ingo Molnar <mingo@elte.hu>, Jeremy Fitzhardinge <jeremy@xensource.com>,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] x86: remove byte locks
References: <alpine.LNX.1.10.0901121247430.5377@jikos.suse.cz> <20090112120743.GC24266@elte.hu> <alpine.LNX.1.10.0901121334510.5377@jikos.suse.cz> <20090112124401.GA31939@elte.hu> <496D1F54.7070104@goop.org> <alpine.LNX.1.10.0901140016520.5377@jikos.suse.cz>
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Jiri Kosina wrote:
> Why can't this just be somewhere in documentation? (possibly even with the 
> byte locks code as a reference).
>   

Because Ingo's compil-o-matic will never fail on a documentation error.

> It is IMHO just totally confusing to have a spinlock implementation that 
> is not used at all in the tree. It took me quite some time to go through 
> this until I finally figured out that this code is actually never used. 
> Currently, on first sight it might seem that byte locks are used whenever 
> CONFIG_PARAVIRT is set, which is not true.
>   

Well, a comment next to the code explaining the rationale probably 
wouldn't go astray.

> And apparently even Linus got confused by this, which also tells us 
> something by itself, see [1].
>
> [1] http://marc.info/?l=linux-kernel&m=123144211719754&w=2
>   

It tells us that Linus couldn't give a rat's arse about virtualization, 
which is just something we have to cope with ;)

    J