IO_RESOURCE_DESCRIPTOR

The IO_RESOURCE_DESCRIPTOR structure describes a range of raw hardware resources, of one type, that can be used by a device. An array of IO_RESOURCE_DESCRIPTOR structures is contained within each IO_RESOURCE_LIST structure.

typedef struct _IO_RESOURCE_DESCRIPTOR {
  UCHAR Option;
  UCHAR Type;
  UCHAR ShareDisposition;
  UCHAR Spare1;
  USHORT Flags;
  USHORT Spare2;
  union {
    struct {
      ULONG Length;
      ULONG Alignment;
      PHYSICAL_ADDRESS MinimumAddress;
      PHYSICAL_ADDRESS MaximumAddress;
    } Port;
    struct {
      ULONG Length;
      ULONG Alignment;
      PHYSICAL_ADDRESS MinimumAddress;
      PHYSICAL_ADDRESS MaximumAddress;
    } Memory;
    struct {
      ULONG MinimumVector;
      ULONG MaximumVector;
    } Interrupt;
    struct {
      ULONG MinimumChannel;
      ULONG MaximumChannel;
    } Dma;
    struct {
      ULONG Length;
      ULONG Alignment;
      PHYSICAL_ADDRESS MinimumAddress;
      PHYSICAL_ADDRESS MaximumAddress;
    } Generic;
    struct {
      ULONG Data[3];
    } DevicePrivate;
    struct {
      ULONG Length;
      ULONG MinBusNumber;
      ULONG MaxBusNumber;
      ULONG Reserved;
    } BusNumber;
    struct {
      ULONG Priority;
      ULONG Reserved1;
      ULONG Reserved2;
    } ConfigData;
  } u;
} IO_RESOURCE_DESCRIPTOR, *PIO_RESOURCE_DESCRIPTOR;

Members

Option

Specifies whether this resource description is required, preferred, or alternative. One of the following values must be used:

Value	Definition
0
	The specified resource range is required, unless alternative ranges are also specified.
IO_RESOURCE_PREFERRED
	The specified resource range is preferred to any alternative ranges.
IO_RESOURCE_ALTERNATIVE
	The specified resource range is an alternative to the range preceding it. For example, if one IO_RESOURCE_DESCRIPTOR structure specifies IRQ 5, with IO_RESOURCE_PREFERRED set, and the next structure specifies IRQ 3, with IO_RESOURCE_ALTERNATIVE set, the PnP Manager assigns IRQ 3 to the device only if IRQ 5 is unavailable. (Multiple alternatives can be specified for each resource. Both IO_RESOURCE_ALTERNATIVE and IO_RESOURCE_PREFERRED can be set, indicating a preferred alternative.)
IO_RESOURCE_DEFAULT
	Not used.

Type

Identifies the resource type. For a list of valid values, see the Type member of the CM_PARTIAL_RESOURCE_DESCRIPTOR structure.

ShareDisposition

Indicates whether the described resource can be shared. For a list of valid values, see the ShareDisposition member of the CM_PARTIAL_RESOURCE_DESCRIPTOR structure.

Flags

Contains bit flags that are specific to the resource type. For a list of valid flags, see the Flags member of the CM_PARTIAL_RESOURCE_DESCRIPTOR structure.

u.Port

Specifies a range of I/O port addresses, using the following members:

Length: The length, in bytes, of the range of assignable I/O port addresses.
Alignment: The alignment, in bytes, that the assigned starting address must adhere to. The assigned starting address must be devisable by Alignment.
MinimumAddress: The minimum bus-relative I/O port address that can be assigned to the device
MaximumAddress: The maximum bus-relative I/O port address that can be assigned to the device

u.Memory

Specifies a range of memory addresses, using the following members:

Length: The length, in bytes, of the range of assignable memory addresses.
Alignment: The alignment, in bytes, that the assigned starting address must adhere to. The assigned starting address must be devisable by Alignment.
MinimumAddress: The minimum bus-relative memory address that can be assigned to the device
MaximumAddress: The maximum bus-relative memory address that can be assigned to the device

u.Interrupt

Specifies an interrupt vector range, using the following members:

MinimumVector: The minimum bus-relative vector that can be assigned to the device.
MaximumVector: The maximum bus-relative vector that can be assigned to the device.

u.Dma

Specifies a DMA setting, using one of the following members:

MinimumChannel: The minimum bus-relative DMA channel that can be assigned to the device.
MaximumChannel: The maximum bus-relative DMA channel that can be assigned to the device.

u.Generic

Not used.

u.DevicePrivate

Reserved for system use.

u.BusNumber

Specifies bus numbers, using the following members:

Length: The number of bus numbers required.
MinBusNumber: The minimum bus-relative bus number that can be assigned to the device.
MaxBusNumber: The maximum bus-relative bus number that can be assigned to the device.
Reserved: Not used.

u.ConfigData

Reserved for system use.

Headers

Defined in wdm.h and ntddk.h. Include wdm.h or ntddk.h.

IO_RESOURCE_DESCRIPTOR

Members

Headers

See Also