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

[Martin J. Bligh]

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.

M.
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