Advanced Configuration and Power Interface Specification

ACPI Source Language (ASL)Reference
19.6.42 ExtendedMemory (Extended Memory Resource Descriptor
Macro)
Syntax
ExtendedMemory (ResourceUsage, Decode, IsMinFixed, IsMaxFixed, Cacheable, ReadAndWrite,
AddressGranularity, AddressMinimum, AddressMaximum, AddressTranslation, RangeLength,
TypeSpecificAttributes, DescriptorName, MemoryRangeType, TranslationType)
Arguments
ResourceUsage specifies whether the Memory range is consumed by this device
(ResourceConsumer) or passed on to child devices (ResourceProducer). If nothing is specified,
then ResourceConsumer is assumed.
Decode specifies whether or not the device decodes the Memory range using positive (PosDecode)
or subtractive (SubDecode) decode. If nothing is specified, then PosDecode is assumed. The 1-bit
field DescriptorName._DEC is automatically created to refer to this portion of the resource
descriptor, where ‘1’ is SubDecode and ‘0’ is PosDecode.
IsMinFixed specifies whether the minimum address of this Memory range is fixed (MinFixed) or
can be changed (MinNotFixed). If nothing is specified, then MinNotFixed is assumed. The 1-bit
field DescriptorName. _MIF is automatically created to refer to this portion of the resource
descriptor, where ‘1’ is MinFixed and ‘0’ is MinNotFixed.
IsMaxFixed specifies whether the maximum address of this Memory range is fixed (MaxFixed) or
can be changed (MaxNotFixed). If nothing is specified, then MaxNotFixed is assumed. The 1-bit
field DescriptorName. _MAF is automatically created to refer to this portion of the resource
descriptor, where ‘1’ is MaxFixed and ‘0’ is MaxNotFixed.
Cacheable specifies whether or not the memory region is cacheable (Cacheable), cacheable and
write-combining (WriteCombining), cacheable and prefetchable (Prefetchable) or uncacheable
(NonCacheable). If nothing is specified, then NonCacheable is assumed. The 2-bit field
DescriptorName._MEM is automatically created to refer to this portion of the resource descriptor,
where ‘1’ is Cacheable, ‘2’ is WriteCombining, ‘3’ is Prefetchable and ‘0’ is NonCacheable.
ReadAndWrite specifies whether or not the memory region is read-only (ReadOnly) or read/write
(ReadWrite). If nothing is specified, then ReadWrite is assumed. The 1-bit field
DescriptorName._RW is automatically created to refer to this portion of the resource descriptor,
where ‘1’ is ReadWrite and ‘0’ is ReadOnly.
AddressGranularity evaluates to a 64-bit integer that specifies the power-of-two boundary (- 1) on
which the Memory range must be aligned. The 64-bit field DescriptorName._GRA is automatically
created to refer to this portion of the resource descriptor.
AddressMinimum evaluates to a 64-bit integer that specifies the lowest possible base address of the
Memory range. The value must have ‘0’ in all bits where the corresponding bit in
AddressGranularity is ‘1’. For bridge devices which translate addresses, this is the address on the
secondary bus. The 64-bit field DescriptorName ._MIN is automatically created to refer to this
portion of the resource descriptor.
AddressMaximum evaluates to a 64-bit integer that specifies the highest possible base address of the
Memory range. The value must have ‘0’ in all bits where the corresponding bit in
AddressGranularity is ‘1’. For bridge devices which translate addresses, this is the address on the
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