Re: SMP/HIGHMEM/7450 status ?

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

>Apple did hold off on dual 7450 until rev 2.1 came out and fixed some
>of the nastier SMP errata, so presumably they at least thought there
>were no SMP showstoppers left in rev 2.1.  As far as I can tell they
>are pretty stable under OS X.

There is an SMP showstopper with HW hashtable walk, but Apple
claims to have a HW workaround.

>Linux is probably just missing some deep magic needed for working
>around one or more of the errata that do still apply to rev 2.1.  The
>trouble is figuring out exactly what's wrong... it can be VERY
>difficult to understand all the ramifications of a CPU bug
>(particularly a SMP related bug) until you use a bus analyzer to
>snapshot bus traffic during a crash, or probe CPU registers via JTAG
>after it has crashed, etc.

Especially since you don't have the connector on the motherboard
to put such a tool, and since I don't even have physical access
to any of these machines.

Ben.


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