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    SubjectRe: [PATCH] MAX_MP_BUSSES increase
    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

    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
    --- 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 @@

    -#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,

    > 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 |
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