Messages in this thread | | | Subject | Re: [RFC 4/6] x86, NMI, Rewrite NMI handler | From | Huang Ying <> | Date | Tue, 14 Sep 2010 13:12:41 +0800 |
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On Mon, 2010-09-13 at 22:04 +0800, Don Zickus wrote: > On Mon, Sep 13, 2010 at 10:09:30AM +0800, Huang Ying wrote: > > > The reason I asked was, I thought it would be easier to have a global > > > variable that tells the nmi handler which cpu has the NMI's routed to its > > > io port. This way if you want to swap out the bsp cpu, you could perhaps > > > just re-route the nmi to a new cpu and the global variable would be > > > updated accordingly? > > > > Then we need some kind of protection or race condition between > > re-routing NMI and updating the variable. Do you think so? > > Well, I thought the only reasonable place to update the variable is when > the cpu is being taken offline, during the MTRR update. Since no NMIs can > be processed when the cpu's are syncing their MTRR, there shouldn't be a > race condition, no? > > Then again I am probably missing something obvious. Like I don't know how > cpu's deal with interrupts/NMIs when they are going offline. > > It was just a thought to avoid the spinlock.
Why do you hate spinlock inside NMI handler? I think it is safe and simple if only used in NMI handler.
Best Regards, Huang Ying
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