Creating Varying Resource Maps
While standard resource maps can only assign an entire parent resource to a child of a multifunction device, varying resource maps let you subdivide a parent resource among children enumerated by mf.sys. Varying resource maps are supported on Windows XP and later versions of the NT-based operating system.
For example, consider a multiport serial card on the PCI bus. Assume each of the card's 16550 UART functions requires a set of eight I/O ports and a single, shared interrupt. Also assume that the card is implemented as a single PCI function. In this scenario, it is typical to request a single block of I/O ports and to then split this block into eight segments, one for each 16550 UART function.
In addition to the I/O port and interrupt resources required by the card's 16550 UART functions, assume that the device also requires memory ranges and device-private resources.
Based on these assumptions, mf.sys will return a resource requirements list for this device, constructed as follows:
| Resourcenumber | Resource |
|---|---|
| 00 | Memory Range Base Register Address (BAR) 0 |
| 01 | Private Data |
| 02 | Memory Range BAR 1 |
| 03 | Private Data |
| 04 | I/O Port Range BAR 2 |
| 05 | Private Data |
| 06 | Interrupt |
Vendors use INF file directives to specify the sharing of these resources among the card's 16550 UART functions. For each function that requires a segment of the device's resources, you must use a VaryingResourceMap entry in the INF to create a registry entry. Following is an excerpt from the INF file for this device:
[DDInstall.RegHW]
; for each "child" function list hardware ID and resource map
; and/or varying resource map
HKR,Child0002,HardwareID,, child0002-hardware ID
HKR,Child0002,VaryingResourceMap,1,04, 10,00,00,00, 08,00,00,00
HKR,Child0002,ResourceMap,1,06
The line containing VaryingResourceMap is interpreted as follows:
The "1" following the VaryingResourceMap parameter specifies that the registry entry's data type is REG_BINARY.
The numbers following the "1" are the varying resource map values. The '04' indicates the parent resource, a segment of which we are assigning to this child. In this case, we're assigning a segment of resource 04 (BAR 2) to the child (that is, a piece of the resource representing the eight I/O port ranges for each serial port).
The next two DWORDs indicate, first, the offset into the resource and, second, the length of the range that should be allocated to this child. In this case, eight I/O ports are being allocated to this child, starting at offset 0x10 into the parent resource.
If this child required another parent resource, the resource's number, length, and offset would be included on the same line of the INF, following the first resource.
The ResourceMap parameter is described in Creating Standard Resource Maps and indicates that this child should get a share of resource 06, which in this case is the PCI device's interrupt.
Following is a more complete example for this device, specifying four child functions:
[Version]
Signature="$Windows NT$"
Class=MultiFunction
ClassGUID={4d36e971-e325-11ce-bfc1-08002be10318}
Provider=%MYCOMPANY%
DriverVer=1/20/2000
CatalogFile=ExampleCatalog.cat
PnpLockdown=1
[ControlFlags]
ExcludeFromSelect=*
[Manufacturer]
%MYCOMPANY%=MYCOMPANY,NTamd64
[MYCOMPANY.NTamd64]
%MYCOMPANY_4PORT%=MYCOMPANY4PORT_inst, PCI\VEN_10B5&DEV_9050&SUBSYS_003112E0
[MYCOMPANY4PORT_inst]
Include = mf.inf
Needs = MFINSTALL.mf
[MYCOMPANY4PORT_inst.HW]
AddReg=MYCOMPANY4PORT_inst.RegHW
[MYCOMPANY4PORT_inst.Services]
Include = mf.inf
Needs = MFINSTALL.mf.Services
[MYCOMPANY4PORT_inst.RegHW]
HKR,Child0000,HardwareID,,*PNP0501
HKR,Child0000,VaryingResourceMap,1,04, 00,00,00,00, 08,00,00,00
HKR,Child0000,ResourceMap,1,06
HKR,Child0001,HardwareID,,*PNP0501
HKR,Child0001,VaryingResourceMap,1,04, 08,00,00,00, 08,00,00,00
HKR,Child0001,ResourceMap,1,06
HKR,Child0002,HardwareID,,*PNP0501
HKR,Child0002,VaryingResourceMap,1,04, 10,00,00,00, 08,00,00,00
HKR,Child0002,ResourceMap,1,06
HKR,Child0003,HardwareID,,*PNP0501
HKR,Child0003,VaryingResourceMap,1,04, 18,00,00,00, 08,00,00,00
HKR,Child0003,ResourceMap,1,06
[Strings]
MYCOMPANY= "MYCOMPANY Inc."
MYCOMPANY_4PORT="MYCOMPANY 4PORT"