On 06/06/2016 09:38 AM, Jan Beulich wrote:
>>>> On 06.04.16 at 03:25, <boris.ostrov...@oracle.com> 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) ..." -boris > >> --- a/xen/common/libacpi/build.c >> +++ b/xen/common/libacpi/build.c >> @@ -555,6 +555,8 @@ void acpi_build_tables(struct acpi_config *config, >> unsigned long physical) >> fadt->x_dsdt = config->mem_ops.v2p(dsdt); >> fadt->firmware_ctrl = config->mem_ops.v2p(facs); >> fadt->x_firmware_ctrl = config->mem_ops.v2p(facs); >> + if ( !(config->table_flags & ACPI_BUILD_IOAPIC) ) >> + fadt->flags |= (1<<20); /* HW_REDUCED_ACPI */ > I think this would better be made a suitable #define in acpi2_0.h. > > Jan > _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
