A slight atmospheric problem
Andreas Stiller wrote in his “Prozessorgeflüster” column (the last remaining island of constant high quality in the c’t) about a nasty in the Intel Nehalem. For i7 900 you will find the errata at “AAJ121. Unexpected Interrupts May Occur on C6 Exit If Using APIC Timer to Generate Interrupts” in the pdf Intel® CoreTM i7-900 Desktop Processor Extreme Edition Series and Intel® CoreTM i7-900 Desktop Processor Series. For other Nehalem procs you will find matching reports under AAK119 for Xeon 5500, AAM123 for Xeon 3500, AAO89 for Xeon 3400 and AAN87 (Core i7-800, Core i5). That’s not that interesting … bugs in CPUs are quite common
However Intel thought, that this bug isn’t triggered by any commercially available software.Well … not exactly. There is one: Windows Server 2008 R2 with enabled Hyper-V. An hot fix is available, but the interims workaround is really interesting: Switching those C-states and thus power-saving. But you will kill the Turbo Boost feature as well with such a step, as Turbo Boost is the other side of the medal of the Power Saving feature.
But that isn’t still the most interesting point of this bug. The most interesting part is a atmospheric one. The relation between Intel and Microsoft must have experienced a cool down recently. ;) Andreas Stiller writes in his article:
And it gets worse: the editorial office received a non-published raw version of the error report that even included the brusque “preferred solution” of not using the processors in question. Strong stuff: Microsoft advises against the application of Nehalem processors in servers – so Intel took to the barricades and was able to prevent Microsoft publishing this advice at the very last second.
I would have really liked to see the reaction of the usual news outlets and the market, when Intel would have not been able to convince Microsoft to change the report ;)