Description

The MmGetMdlVirtualAddress macro returns the base virtual address of a buffer described by an MDL.

Syntax

#define MmGetMdlVirtualAddress(Mdl) \
    ((PVOID) ((PCHAR) ((Mdl)->StartVa) + (Mdl)->ByteOffset))

Parameters

Mdl [in]

Pointer to an MDL that describes the buffer for which to return the initial virtual address.

Return value

MmGetMdlVirtualAddress returns the base virtual address of the buffer described by the MDL.

Remarks

MmGetMdlVirtualAddress returns the starting virtual address of the MDL.

MmGetMdlVirtualAddress returns a virtual address that is not necessarily valid in the current thread context. Lower-level drivers should not attempt to use the returned virtual address to access memory, particularly user memory space.

The returned address, used as an index to a physical address entry in the MDL, can be input to MapTransfer.

Callers of MmGetMdlVirtualAddress can be running at any IRQL. Usually, the caller is running at IRQL = DISPATCH_LEVEL because this routine is commonly called to obtain the _CurrentVa_ parameter to MapTransfer.