NdisMFreeSharedMemory function

Description

NdisMFreeSharedMemory frees memory that was previously allocated by NdisMAllocateSharedMemory or NdisMAllocateSharedMemoryAsyncEx by the driver of a DMA NIC.

Parameters

MiniportAdapterHandle [in]

Specifies the handle originally input to MiniportInitializeEx.

Length [in]

Specifies the number of bytes originally allocated.

Cached [in]

Specifies TRUE if the original allocation was cacheable.

VirtualAddress [in]

Specifies the base virtual address returned by NdisMAllocateSharedMemory or NdisMAllocateSharedMemoryAsyncEx.

PhysicalAddress [in]

Specifies the corresponding physical address returned by NdisMAllocateSharedMemory or NdisMAllocateSharedMemoryAsyncEx.

Remarks

If it has already made a successful call to NdisMAllocateSharedMemory or NdisMAllocateSharedMemoryAsyncEx, the miniport driver of a DMA device calls NdisMFreeSharedMemory if any of the following occurs:

• Its MiniportInitializeEx function is unable to initialize the NIC, so this function must release all existing claims on hardware resources for that NIC before it returns control.
• The NIC for which the miniport driver allocated the memory is being removed.
• The driver is being unloaded, whether because the system is shutting down or because the user reconfigured the network components used in the machine.
• The driver allocated additional shared memory with NdisMAllocateSharedMemoryAsyncEx when I/O demand on a NIC was high but network traffic has now subsided to an average level.

A miniport driver cannot call NdisMFreeSharedMemory to free a subrange within an allocated shared memory range. The parameters passed to NdisMFreeSharedMemory must match exactly those that were passed to NdisMAllocateSharedMemory or NdisMAllocateSharedMemoryAsyncEx.

NdisMFreeSharedMemory cannot be called from a MiniportShutdownEx function.

Microsoft Windows Server 2003, Windows XP Service Pack 1, and later versions of Windows allow both bus-master DMA NICs and subordinate DMA NICs to call NdisMFreeSharedMemory. Prior releases allow only bus-master DMA NICs to call NdisMFreeSharedMemory.

See also

MiniportHaltEx

MiniportInitializeEx

MiniportSharedMemoryAllocateComplete

MiniportShutdownEx

NdisMAllocateSharedMemory

NdisMAllocateSharedMemoryAsyncEx