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From: James Cleverdon <jamesclv@us.ibm.com>
Reply-To: jamesclv@us.ibm.com
Organization: IBM xSeries Linux (NUMA)
To: Marcelo Tosatti <marcelo@conectiva.com.br>
Subject: Re: [PATCH] MAX_MP_BUSSES increase
Date: Tue, 8 Jan 2002 01:14:16 -0800
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Cc: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@transmeta.com>
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Back from holiday.

On Wednesday 26 December 2001 07:43 am, Marcelo Tosatti wrote:
> James,
>
> Don't remove the "#ifdef CONFIG_MULTIQUAD" on your patch: Let the old max
> (32) for non-multiquad machines.

There's a problem with that -- despite its name, CONFIG_MULTIQUAD is used for 
the old NUMA-Q hardware.  It turns on some memory mapped port I/O code that 
doesn't have any purpose for other machines.  The PCI bus overflow happens on 
our new Foster-based boxes that may or may not contain multiple quad CPU 
boards.

Still, CONFIG_MULTIQUAD is better than nothing.  It just may take a little 
bit of redefinition, so long as we can coax the various distros to build 
their installation and working kernels with CONFIG_MULTIQUAD turned on....

> Please resend me the patch this way.

OK, what do you think about this:

diff -ru 2.4.17/include/asm-i386/mpspec.h 
jamesc-2.4.17/include/asm-i386/mpspec.h
--- 2.4.17/include/asm-i386/mpspec.h	Thu Nov 22 11:46:18 2001
+++ jamesc-2.4.17/include/asm-i386/mpspec.h	Tue Jan  8 01:00:12 2002
@@ -185,12 +186,13 @@
  */
 
 #ifdef CONFIG_MULTIQUAD
-#define MAX_IRQ_SOURCES 512
+#define MAX_MP_BUSSES	257	/* Need max PCI busses for hotplug + 1 for ISA. */
+#define MAX_IRQ_SOURCES (MAX_MP_BUSSES * 4)	/* Four intrs per PCI slot. */
 #else /* !CONFIG_MULTIQUAD */
+#define MAX_MP_BUSSES	32
 #define MAX_IRQ_SOURCES 256
 #endif /* CONFIG_MULTIQUAD */
 
-#define MAX_MP_BUSSES 32
 enum mp_bustype {
 	MP_BUS_ISA = 1,
 	MP_BUS_EISA,



> On Wed, 19 Dec 2001, James Cleverdon wrote:
> > We've run into a bit of a problem with a forthcoming system.  The BIOS
> > reserves so many PCI bus numbers for hotplug when maxed out PCI expansion
> > box(es) are present that some arrays (mp_bus_id_to_node[],
> > mp_bus_id_to_pci_bus[], etc) overflow, splattering important variables.

-- 
James Cleverdon, IBM xSeries Platform (NUMA), Beaverton
jamesclv@us.ibm.com   |   cleverdj@us.ibm.com

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