linux-kernel - Re: [Patch] convert i386 Summint subarch to use SRAT info for apicid_to

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Date:	Thu, 20 Jul 2006 13:24:20 -0700
From:	keith mannthey <kmannth@...ibm.com>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	andrew <akpm@...l.org>
Subject: Re: [Patch] convert i386 Summint subarch to use SRAT info for
	apicid_to_node calls

On Wed, 2006-07-19 at 17:11 -0700, keith mannthey wrote:
> Hello Andrew,
>   This patch converts the i386 summit subarch apicid_to_node to use node
> information provided by the SRAT.  It was discussed a little on LKML a
> few weeks ago and was seen as an acceptable fix.  The current way of
> obtaining the nodeid 
> 
>  static inline int apicid_to_node(int logical_apicid)
>  { 
>    return logical_apicid >> 5;
>  }
> 
> is just not correct for all summit systems/bios.  Assuming the apicid
> matches the Linux node number require a leap of faith that the bios
> mapped out the apicids a set way.  Modern summit HW (IBM x460) does not
> layout its bios in the manner for various reasons and is unable to boot
> i386 numa.
> 
>   The best way to get the correct apicid to node information is from the
> SRAT table during boot.  It lays out what apicid belongs to what node.
> I use this information to create a table for use at run time. 
> 
>   The attached patch was built against 2.6.18-rc1.  It only changes the
> summit subarch.  
> 

Attached updated patch to deal with non-numa Summit config options.   A
build error was reported when booting with numa off and Summit / Genarch
selected.  

Signed-off-by:  Keith Mannthey <kmannth@...ibm.com>


View attachment "patch-2.6.18-rc1-apicid_to_node_srat-v3" of type "text/x-patch" (3370 bytes)