MmMapIoSpaceEx - NtDoc
Native API online documentation, based on the System Informer
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headers
// wdm.h
PVOID MmMapIoSpaceEx(
[in] PHYSICAL_ADDRESS PhysicalAddress,
[in] SIZE_T NumberOfBytes,
[in] ULONG Protect
);
View the official Windows Driver Kit DDI referenceNo description available.
The MmMapIoSpaceEx routine maps the given physical address range to non-paged system space using the specified page protection.
PhysicalAddress [in]Specifies the starting physical address of the I/O range to be mapped.
NumberOfBytes [in]Specifies a value greater than zero, indicating the number of bytes to be mapped.
Protect [in]Flag bits that specify the protection to use for the mapped range. The caller must set one of the following flag bits in the Protect parameter.
| Flag bit | Meaning |
|---|---|
| PAGE_READONLY | The mapped range can only be read, not written. |
| PAGE_READWRITE | The mapped range can be read or written. |
| PAGE_EXECUTE | The mapped range can be executed, but not read or written. |
| PAGE_EXECUTE_READ | The mapped range can be executed or read, but not written. |
| PAGE_EXECUTE_READWRITE | The mapped range can be executed, read, or written. |
In addition, the caller can set one (but not both) of the following optional flag bits in the Protect parameter.
| Flag bit | Meaning |
|---|---|
| PAGE_NOCACHE | Specifies non-cached memory. |
| PAGE_WRITECOMBINE | Specifies write-combined memory (the memory should not be cached by the processor, but writes to the memory can be combined by the processor). |
MmMapIoSpaceEx returns the base virtual address that maps the base physical address for the range. If space for mapping the range is insufficient, it returns NULL.
A driver must call this routine during device start-up if it receives translated resources of type CmResourceTypeMemory in a CM_PARTIAL_RESOURCE_DESCRIPTOR structure. MmMapIoSpaceEx maps the physical address returned in the resource list to a virtual address through which the driver can access device registers.
For example, drivers of PIO devices that allocate long-term I/O buffers can call this routine to make such buffers accessible or to make device memory accessible.
For more information about using this routine, see Mapping Bus-Relative Addresses to Virtual Addresses.