Re: [RFC] patch [1/1] convert i386 summit subarch to use SRAT data for apicid_to_node

[keith mannthey <kmannth@us.ibm.com>]

On Wed, 2006-06-21 at 22:24 -0400, Dave Jones wrote:
> On Wed, Jun 21, 2006 at 06:54:55PM -0700, keith mannthey wrote:
>  > Hello All,
>  >   This patch converts the i386 summit subarch apicid_to_node to use node
>  > information provided by the SRAT.  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 lay-
>  > ed out the apicids a set way.  Modern summit HW 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. 
> 
> Do all summit's have SRAT tables ?
> I was under the impression the early ones were around before
> the invention of SRAT.

That is a good point.  Let me check into the x440 (1st gen).  x445 x460
(2nd,3rd gen) uses SRAT for sure (these patches have been tested on
these systems).  

The x440 lists an srat but maybe it is using some special bios area.  I
will build a test kernel give it a whirl.  


> 		Dave
> 
-- 
keith mannthey <kmannth@us.ibm.com>
Linux Technology Center IBM