Messages in this thread | | | From | (Eric W. Biederman) | Date | Sat, 12 Jul 2008 01:11:49 -0700 | Subject | Re: [patch 00/26] x64, x2apic/intr-remap: Interrupt-remapping and x2apic support |
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"Yinghai Lu" <yhlu.kernel@gmail.com> writes:
>>> also read the x2APIC spec pdf, it doesn't say anything about interrupt >>> remapping...need to be used with x2apic... >> >> Clustered logical mode won't work as it requires > 16 bits of apicid. >> So only flat physical mode will work. > > current read_apic_id in genx2apic_cluster and genx2apic_phys is the same...
There is a fixed defined mapping between logical & physical mappings, so that may not be an issue.
A logical cluster apicid is encoded with the high 16bits being the cluster number, and the low 16bits being a bitmap of which core in the cluster to send the irq to. It sounded like a single cluster can not span multiple sockets.
So in practice if you have 2 sockets you have a cluster id of 1. Which means physical apic ids over 16 and logical apicids over 65536.
Eric
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