Messages in this thread | | | Subject | Re: x2apic boot failure on recent sandy bridge system | From | Suresh Siddha <> | Date | Sun, 11 Dec 2011 23:23:22 -0800 |
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On Sun, 2011-12-11 at 13:43 -0800, Yinghai Lu wrote: > -v4: according to Ingo, for x2apic pre-enabled system, if intr-remap can not > be enabled, try to disable x2apic instead of panic and request to > specify nox2apic for next boot.
If bios has not exported any DMAR tables but enabled x2apic pre-boot, it is tricky for the OS to disable x2apic and continue with xapic for number of reasons. For example, if chipset has already enabled interrupt-remapping (which is typically recommended to be enabled before x2apic) but didn't provide DMAR tables, then there is no way OS can disable interrupt-remapping in this case.
So even though the cpu might be back in xapic mode, but external interrupts won't work.
thanks, suresh
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