Re: [PATCH] MAX_MP_BUSSES increase

Martin J. Bligh (Martin.Bligh@us.ibm.com)
Tue, 08 Jan 2002 01:41:55 -0800


> 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....

That's not a good idea. You're going to introduce extra switches to every port
IO path, and every IPI (for everybody, not just yourself). CONFIG_MULTIQUAD
is also used to alter the way that PCI config space writes are done (in later
patches). I suggest you use a different config option, or construct it dynamically.

Martin.

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