The build_ssdt() function builds a number of AML objects that are related
to CPU hotplug, and whose IDs form a contiguous sequence of APIC IDs.
(APIC IDs are in fact discontiguous, but this is the traditional
interface: build a contiguous sequence from zero up that covers all
possible APIC IDs.) These objects are:
- a Processor() object for each VCPU,
- a NTFY method, with one branch for each VCPU,
- a CPON package with one element (hotplug status byte) for each VCPU.
The build_ssdt() function currently limits the *count* of processor
objects, and NTFY branches, and CPON elements, in 0xFF (see the assignment
to "acpi_cpus"). This allows for an inclusive APIC ID range of [0..254].
This is incorrect, because the highest APIC ID that we otherwise allow a
VCPU to take is 255.
In order to extend the maximum count to 256, and the traversed APIC ID
range correspondingly to [0..255]:
- the Processor() objects need no change,
- the NTFY method also needs no change,
- the CPON package must be updated, because it is defined with a
DefPackage, and the number of elements in such a package can be at most
255. We pick a DefVarPackage instead.
We replace the Op byte, and the encoding of the number of elements.
Compare:
DefPackage := PackageOp PkgLength NumElements PackageElementList
DefVarPackage := VarPackageOp PkgLength VarNumElements PackageElementList
PackageOp := 0x12
VarPackageOp := 0x13
NumElements := ByteData
VarNumElements := TermArg => Integer
The build_append_int() function implements precisely the following TermArg
encodings (a subset of what the ACPI spec describes):
TermArg := DataObject
DataObject := ComputationalData
ComputationalData := ConstObj | ByteConst | WordConst | DWordConst
directly encoded in the function, with build_append_byte():
ConstObj := ZeroOp | OneOp
ZeroOp := 0x00
OneOp := 0x01
call to build_append_value(..., 1):
ByteConst := BytePrefix ByteData
BytePrefix := 0x0A
ByteData := 0x00 - 0xFF
call to build_append_value(..., 2):
WordConst := WordPrefix WordData
WordPrefix := 0x0B
WordData := ByteData[0:7] ByteData[8:15]
call to build_append_value(..., 4):
DWordConst := DWordPrefix DWordData
DWordPrefix := 0x0C
DWordData := WordData[0:15] WordData[16:31]
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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