On Fri, 15 Jun 2018, Ricardo Neri wrote: > On Fri, Jun 15, 2018 at 12:29:06PM +0200, Thomas Gleixner wrote: > > You have to consider two cases: > > > > 1) !remapped mode: > > > > That's reasonably simple because you just have to deal with the HPET > > TIMERn_PROCMSG_ROUT register. But then you need to do this directly and > > not through any of the existing interrupt facilities. > > Indeed, there is no need to use the generic interrupt faciities to set affinity; > I am dealing with an NMI anyways. > > > > 2) remapped mode: > > > > That's way more complex as you _cannot_ ever do anything which touches > > the IOMMU and the related tables. > > > > So you'd need to reserve an IOMMU remapping entry for each CPU upfront, > > store the resulting value for the HPET TIMERn_PROCMSG_ROUT register in > > per cpu storage and just modify that one from NMI. > > > > Though there might be subtle side effects involved, which are related to > > the acknowledge part. You need to talk to the IOMMU wizards first. > > I see. I will look into the code and prototype something that makes sense for > the IOMMU maintainers. I'd recommend to talk to them _before_ you cobble something together. If we cannot reliably switch the affinity by directing the HPET NMI to a different IOMMU remapping entry then the whole scheme does not work at all. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
