NVME_PRP_ENTRY union (nvme.h)

Contains fields that specify the Page Base Address and Offset (PBAO) of a pointer to a physical memory page.

A Physical Region Page (PRP) Entry is a pointer to a physical memory page. PRPs are used as a scatter/gather mechanism for data transfers between the controller and memory. To enable efficient out of order data transfers between the controller and the host, PRP entries are a fixed size.

The size of the physical memory page is configured by host software in the MPS field of the Controller Configuration structure, and the size of the Offset field is determined by the MPS value.

This structure is used in the PRP1 and PRP2 fields of the NVME_COMMAND structure.

Syntax

typedef union {
  struct {
    ULONGLONG Reserved0 : 2;
    ULONGLONG PBAO : 62;
  } DUMMYSTRUCTNAME;
  ULONGLONG AsUlonglong;
} NVME_PRP_ENTRY, *PNVME_PRP_ENTRY;

Members

DUMMYSTRUCTNAME

DUMMYSTRUCTNAME.Reserved0

A reserved field.

DUMMYSTRUCTNAME.PBAO

Indicates the 64-bit physical memory page address.

The lower bits (n:2) of this field indicate the offset within the memory page. If the memory page size is 4KB, then bits 02:11 form the Offset; if the memory page size is 8KB, then bits 02:12 form the Offset, and so on.

If this entry is not the first PRP entry in the command or a PRP List pointer in a command, then the Offset portion of this field should be cleared to 0h.

AsUlonglong

Requirements

Requirement	Value
Minimum supported client	Windows 10
Header	nvme.h