linux-kernel - Re: x86: unify genapic code, unify subarchitectures, remove old subarchitecture code

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Message-ID: <20090130090136.GA18453@one.firstfloor.org>
Date:	Fri, 30 Jan 2009 10:01:36 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Tim Pepper <lnxninja@...ux.vnet.ibm.com>,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: x86: unify genapic code, unify subarchitectures, remove old subarchitecture code

> At this point there's no technical need to kill it - it's a zero-overhead 
> thing tucked away into a single .c module in arch/x86/kernel/numaq_32.c. I 
> even consolidated most of its headers in that file, to reduce its cross 
> section.

There's still a couple of hooks in the subarch interface (even your new one) 
which are effectively NUMAQ only. These are far from zero overhead. Plus the
ugly wards in smpboot.c like the special path to wake up CPUs via NMI and
some other things. And the hacks like the special ECR access. NUMAQ is really
very very different from a normal PC and needed a lot of special code. 

Even with your changes removing NUMAQ would be a significant cleanup.

Also BTW if it hasn't been tested it's unlikely to work and
keeping code around that doesn't work doesn't seem very useful.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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