On 02/01/17 12:37, Igor Mammedov wrote: > On Tue, 31 Jan 2017 20:17:02 +0200 > "Michael S. Tsirkin" <m...@redhat.com> wrote: > >> On Tue, Jan 31, 2017 at 05:28:57PM +0100, Laszlo Ersek wrote: >>> The ACPI 6.1 spec says, >>> >>> - DSDT: [...] If the X_DSDT field contains a non-zero value then this >>> field must be zero. >>> - X_DSDT: [...] If the DSDT field contains a non-zero value then this >>> field must be zero. >> >> But that's only 6.1. 6.0 and earlier did not say this. >> The errata they wanted to address was: >> 1393 In FADT: if X_DSDT field is non-zero, DSDT >> field should be ignored or deprecated >> >> I would class this as a spec bug. >> > > The same applies to X_PM1a_EVT_BLK and co, > for example 5.1 spec "This is a required > field." > > And looks like Windows implemented it as mandatory > to boot perhaps to be compatible with 5.1 and earlier > specs. > > It appears fw would be forced to fill fields depending > on table revision.
Sounds like a valid point. I compared the FADT defintion between ACPI 5.1 and ACPI 6.1. Indeed, the former says: - FADT Major Version: 5; Major Version of this FADT structure, [...] - DSDT: Physical memory address (0-4 GB) of the DSDT. - X_DSDT: 64bit physical address of the DSDT. the latter says: - FADT Major Version: 6; Major Version of this FADT structure, [...] - DSDT: Physical memory address of the DSDT. If the X_DSDT field contains a non-zero value then this field must be zero. - X_DSDT: Extended physical address of the DSDT. If the DSDT field contains a non-zero value then this field must be zero. I will ask on edk2-devel whether the "MdeModulePkg/Universal/Acpi/AcpiTableDxe" maintainers can think of a way to accommodate this. Thanks Laszlo
