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SubjectRe: [RFC] arch generic way to trigger unknown NMIs
On Sat, 16 Oct 2010, Cyrill Gorcunov wrote:

> > > Hi Maciej, the send_IPI_self could be modified to send NMI (at moment it
> > > uses self shortcut with fixed delivery mode). The question is rather if
> > > we need it without a real caller yet. When Don's patch gets merged we
> > > will have a real caller then and could update send_IPI_self to support
> > > NMI delivery mode. Something like that :)
> >
> > Sounds backwards to me. My understanding is a need has just arisen, so
> > why not:
> >
> > 1. Update send_IPI_self().
> >
> > 2. Add code that makes use of the new functionality.
> >
> > 3. Submit all the changes as self-contained patches in a single series to
> > be applied at the same time.
> >
> > ? That's what I'd imagine the most natural way of doing this would be.
>
> Well, Maciej I believe the problem is not in modifying send_IPI_self
> but rather _how_ to make it more natural and do not introduce overhead.
> apic code is already weird enough :) Need to think.
>
> (
> btw, we will have to add additional flag which would check for NMI
> being generated by "NMI-tester" and make a second apic write to
> ICR to deassert level line, ie it could be something like
>
> apic->send_IPI_self(NMI_VECTOR) ; with asserts level
> default_do_nmi() ; check for NMI being sent for testing purpose
> apic->send_IPI_self(NMI_VECTOR) ; with deasserts level
>
> iirc apic itself doesn't deassert nmi line on message with
> nmi deliver mode arrival
> )

How different is it to the other two send_IPI shorthand calls? Or the
fully-fledged one? I gather from this thread they already handle NMIs
properly, so what is there within that cannot simply be copied over to
this one?

Maciej


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