9 Replies Latest reply on Jul 21, 2016 2:28 PM by rguevara

    Do I have to shutdown IO-APIC before Local APIC

    pandawei

      Hi guys,

       

      I found a bug of kernel that seems be related to the shutdown sequence  between io-apic and local-apic .

       

      I had reported it at LKML: "Wei, Jiangang": Re: RFC: Fix kdump failed with 'notsc' .

       

      I don't find any descriptions about the sequence of disable IO-APIC and Local APIC in "Intel 64 and IA-32 Architectures software developer's manual volume 3A".

      Only erratum AVR31 for "Intel Atom Processor C2000 Product Family Specification Update".

       

      AVR31. Interrupts That Target an APIC That is Being Disabled May Result in a System Hang

      Problem: Interrupts that target a Logical Processor whose Local APIC is either in the process of being hardware disabled by clearing by bit 11 in the IA32_APIC_BASE_MSR or software

      disabled by clearing bit 8 In the Spurious-Interrupt Vector Register at offset 0F0H from the APIC base are neither delivered nor discarded.

      Implication: When this erratum occurs, the processor may hang.

      Workaround: None identified. Software must follow the recommendation that all interrupt sources that target an APIC must be masked or changed to no longer target the APIC before

      the APIC is disabled.

      Status: For the steppings affected, see Table 1, “Errata Summary Table” on page 9.

       

      My machine is Lenovo's QiTianM4340,

      and the CPU is Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz, 4Cores.

       

      Do I have to shutdown IO-APIC before Local APIC for Core(TM) series ?