Messages in this thread | | | Date | Fri, 20 Feb 2009 20:40:54 +0100 | From | Ingo Molnar <> | Subject | Re: smp.c && barriers (Was: [PATCH 1/4] generic-smp: remove single ipi fallback for smp_call_function_many()) |
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* Suresh Siddha <suresh.b.siddha@intel.com> wrote:
> > So the question is, is an SFENCE there enough to serialize > > the WRMSR with previous memory-writes? It's not specified in > > the x2apic docs as far as i could see. > > No. sfence is not enough (wrmsr to x2apic regs was still > passing ahead). We have done a small experiment to demonstrate > the issue and adding mfence fixes the issue but not sfence. We > need a serializing instruction or mfence. I will try to get > the SDM updated.
Fair enough!
Ingo
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