63:42

0h

RO

Reserved

41:16

0h

RW

PMBAR Address (PMBAR)

This field corresponds to bits 41 to 16 of the base address PMBAR address space.
BIOS will program this register resulting in a base address for a 32KB block of contiguous memory address space.
This register ensures that a naturally aligned 32KB space is allocated within total addressable memory space.

15:4

0h

RO

Address Mask (ADDRESS_​MASK)

Hardwired to 0s to indicate at least 32KB address range.
Software typically writes all 1's to the BAR and then reads back the resulting value to assess the size of the BAR.
Since bits 14:4 are read-only and zero, that indicates that the device is 32KB.

3

0h

RO

BAR is Prefetchable (PREFETCHABLE)

Value of 0 indicates the BAR cannot be prefetched.

2:1

2h

RO

Address Range (ADDRESS_​RANGE)

Address Range: Value of 0x2 indicates that the BAR is located anywhere system memory space (i.e. 64-bit addressing).
This also indicates that the size of the BAR register is 64b.

0

0h

RO

Memory Space Indicator (SPACE_​TYPE)

Value of 0 indicates the BAR is located in memory space.