Messages in this thread | | | Date | Tue, 29 Apr 2014 20:48:34 +0200 (CEST) | From | Jiri Kosina <> | Subject | Re: 64bit x86: NMI nesting still buggy? |
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On Tue, 29 Apr 2014, Steven Rostedt wrote:
> > Just to be clear here -- I don't have a box that can reproduce this; I > > whole-heartedly believe that even if there are boxes with this behavior > > (and I assume there are, otherwise Intel wouldn't be mentioning it in the > > docs), it'd be hard to trigger on those. > > I see your point. But it is documented for those that control both NMIs > and SMMs. As it says in the document: "If the SMI handler requires the > use of NMI interrupts". That to me sounds like a system that has > control over both SMIs *and* NMIs. The BIOS should not have any control > over NMIs, as the OS requires that. And the OS has no control over > SMIs. > > That paragraph sounds irrelevant to normal BIOS and OS systems as > neither "owns" both SMIs and NMIs.
Which doesn't really help me being less nervous about this whole thing.
I don't believe Intel would put a completely arbitrary and nonsencial paragraph into the manual all of a sudden. It'd be great to know the rationale why this has been added in the first place.
> > We were hunting something completely different, and came through this > > paragraph in the Intel manual, and found it rather scary. > > But this is all irrelevant anyway as this is all hypothetical and > there's been no real world bug with this.
One would hope. Again -- I believe if this would trigger here and here a few times a year, everyone would probably atribute it to a "random hang", reboot, and never see the bug again.
-- Jiri Kosina SUSE Labs
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