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 23:36 -0700, Martin J. Bligh wrote:
> keith mannthey wrote:
> > 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.  
> 
> I'm pretty sure they all had SRAT tables - the test machine we use 
> regularly for test.kernel.org (elm3b67) does. The NUMA-Q (x430) doesn't,
> but that's a separate subarch.

Tested ontop of x440 just fine it does use the SRAT.  It doesn't do
anything NUMA-Q like :)

Thanks,
keith mannthey <kmannth@us.ibm.com>
Linux Technology Center IBM