[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH RFC 19/20] acpi: Set HW_REDUCED_ACPI in FADT if IOAPIC is not supported
On 06/07/2016 02:06 AM, Jan Beulich wrote: >>>> On 06.06.16 at 19:31, <boris.ostrovsky@xxxxxxxxxx> wrote: >> On 06/06/2016 09:38 AM, Jan Beulich wrote: >>>>>> On 06.04.16 at 03:25, <boris.ostrovsky@xxxxxxxxxx> wrote: >>>> With this flags set guests will not try to set up SCI. >>> I've just read through the respective ACPI spec section again, and >>> I couldn't find a reference to SCI from there ("Hardware-Reduced >>> ACPI"). Can you clarify this connection please. Also there are other >>> consequences of setting that flag, so in order to understand the >>> reasons behind this change in case of future problems I think the >>> description here will need to be significantly extended, despite the >>> change being so small. >> My understanding is that hardware-reduced platforms don't use ACPI >> Platform Event Model (Sec. 4.1.1) and that model requires SCI (and vice >> versa --- SCI is present when ACPI Platform Event Model is in use). The >> (somewhat indirect) evidence of this is in section 4.6 "The ACPI >> Hardware Model" where is says: "In the ACPI Legacy state, the ACPI event >> model is disabled (no SCIs are generated) ..." > In the sum of all the non-explicit wording I can only convince myself > that SCI is a prereq for the event model. Yet I could see this being > an if-and-only-if, just that I couldn't find any place saying so. > Not sure how I should interpret this: do you (reluctantly, possibly) agree that we can use HW-reduced flag to indicate that SCI is not there? -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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