Messages in this thread | | | Date | Mon, 11 Jul 2011 13:32:53 +0530 | Subject | Re: [BUG] Why does mwait_idle_with_hints() call MWAIT with interrupts disabled ? | From | Tomar <> |
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Mike, Thanks for pointing. This explains it. I was looking at an older manual which did not have mention of this ECX extension.
Thanks, Tomar
> I got curious enough to blow an inch of virtual dust off the manual.. > > Software_Delelopers_Manual_Volume:2A:Instruction_Set_Reference:A-M > > MWAIT for Address Range Monitoring > > For address-range monitoring, the MWAIT instruction operates with the MONITOR > instruction. The two instructions allow the definition of an address at which to wait > (MONITOR) and a implementation-dependent-optimized operation to commence at > the wait address (MWAIT). The execution of MWAIT is a hint to the processor that it > can enter an implementation-dependent-optimized state while waiting for an event > or a store operation to the address range armed by MONITOR. > ECX specifies optional extensions for the MWAIT instruction. EAX may contain hints > such as the preferred optimized state the processor should enter. > For Pentium 4 processors (CPUID signature family 15 and model 3), non-zero values > for EAX and ECX are reserved. Later processors defined ECX=1 as a valid extension > (see below). > > A store to the address range armed by the MONITOR instruction, an interrupt, an NMI > or SMI, a debug exception, a machine check exception, the BINIT# signal, the INIT# > signal, or the RESET# signal will exit the implementation-dependent-optimized > state. An interrupt will cause the processor to exit only if the state was entered with > interrupts enabled or if ECX=1. > ^^^^^^^^^^^ > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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