linux-kernel - Re: [PATCH 4/5] x86, cacheinfo: Make L3 cache info per node

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Message-ID: <20100421210534.GA31028@aftab>
Date:	Wed, 21 Apr 2010 23:05:34 +0200
From:	Borislav Petkov <bp@...64.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	mingo@...e.hu, tglx@...utronix.de, x86@...nel.org,
	linux-kernel@...r.kernel.org, Frank Arnold <frank.arnold@....com>
Subject: Re: [PATCH 4/5] x86, cacheinfo: Make L3 cache info per node

From: "H. Peter Anvin" <hpa@...or.com>
Date: Wed, Apr 21, 2010 at 01:46:29PM -0700

> On 04/15/2010 09:41 AM, Borislav Petkov wrote:
> > +
> > +/* max 8 nodes on a system */
> > +static struct amd_l3_cache * __cpuinitdata l3_caches[8];
> > +
> 
> This makes me very nervous.  Where does this limit come from?  It
> appears completely arbitrary and seems like begging for problems in the
> future.

Right. So, we currently have a 3-bit field for the node id of each node,
in conjunction with the L3 cache this means one L3 cache per node. It is
located in F0x60[2:0]. This field is setup to the proper value by the
BIOS.

But yeah, I see your point. I could try initializing it dynamically
per system so that there are no out of bounds accesses. Let me cook up
something tomorrow.

-- 
Regards/Gruss,
Boris.

--
Advanced Micro Devices, Inc.
Operating Systems Research Center
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