3 Replies Latest reply on Jul 14, 2014 3:41 PM by RJSmith92

    Local (CPU) APIC address?




      I was reading the "Desktop 4th Generation Intel® Core™Processor Family" Datasheet at https://www-ssl.intel.com/content/dam/www/public/us/en/documents/datasheets/4th-gen-core-family-desktop-vol-2-datasheet.pdf


      ...and it shows the Local (CPU) APIC address to be at FEC80000h -


      local APIC.png


      But then underneath it says the following -


      "Memory requests to this range would then be forwarded to the PCI Express* port. This mode is intended for the entry Workstation/Server SKU of the PCH, and would be disabled in typical Desktop systems. When disabled, any access within the entire APIC Configuration space (FEC0_0000h to FECF_FFFFh) is forwarded to DMI."

      This contradicts what the image shows and suggested that FEC0_0000h to FECF_FFFFh will go to the DMI to the I/O Apic.

      I have checked the MADT tables and it shows the local CPU address to be FEE0_0000, which it is on most systems. This then clashes with what is shown to be MSI interrupts.

      2 questions then really,

      Do both the local CPU APIC and MSI interrupts use FEE0_0000h?

      What is this range between FEC8_0000h - FECF_FFFF for?

      My CPU is the Core i5 4570 on the Z87 chipset.


      Any help would be appreciated.


      Kind Regards,

      Robert Smith