Messages in this thread | | | Date | Thu, 10 Jul 2008 18:50:59 -0700 | From | Suresh Siddha <> | Subject | Re: [patch 26/26] x64, x2apic/intr-remap: introduce CONFIG_INTR_REMAP |
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On Thu, Jul 10, 2008 at 04:37:33PM -0700, Yong Wang wrote: > > Is it possible to run in x2apic mode without running in interrupt remapping mode? > > Just send the irqs directly to the cpu? It feels like it should be if an iommu > > doesn't get in the way. > > > > Yes, it is possible to run in x2apic mode without intr-remap. However, the extended > cpu addressability will not be fully utilized that way.
No. CPU can't be in x2apic mode with out enabling interrupt-remapping. Interrupts may not work (even when we have few cpu's). For example, in logical cluster mode, logical x2apic id (initialized by HW) will be > 16 bit, in a smaller DP configuration.
In general, enabling x2apic with out enabling interrupt-remapping is not recommended, as the platform will be using legacy interrupt format and the CPU will be using extended ID mode.
thanks, suresh
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