Messages in this thread | | | Date | Mon, 20 Jan 2014 00:56:47 -0800 | From | "H. Peter Anvin" <> | Subject | Re: linux-next: build failure after merge of the tip tree |
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On 01/20/2014 12:26 AM, Peter Zijlstra wrote: > On Sun, Jan 19, 2014 at 11:45:43PM -0500, Len Brown wrote: >> +static void mwait_idle(void) >> +{ >> + mwait_idle_with_hints(0, 0); >> +} >> + >> >> The reason the patch above will crash Core2 machines is because >> core2 machines don't support mwait_idle_with_hints(). >> >> The calling sequence for old and new MWAIT instructions is different. >> The former must be invoked with interrupts enabled, >> and the later can be invoked with interrupts disabled, >> which is a feature that Linux takes advantage of. > > What old and new? They're the same byte sequence: 0x0f 0x01 0xc9 > > And your 'old' __sti_mwait(0,0) has the exact same arguments as > mwait_idle_with_hints(0,0). >
The difference is the STI!
-hpa
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