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nc-netdma-dma_append_handler.md

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UID title description old-location tech.root ms.date keywords ms.keywords req.header req.include-header req.target-type req.target-min-winverclnt req.target-min-winversvr req.kmdf-ver req.umdf-ver req.ddi-compliance req.unicode-ansi req.idl req.max-support req.namespace req.assembly req.type-library req.lib req.dll req.irql targetos req.typenames f1_keywords topic_type api_type api_location api_name
NC:netdma.DMA_APPEND_HANDLER
DMA_APPEND_HANDLER (netdma.h)
The ProviderAppendDma function appends a linked list of DMA descriptors to the last descriptor on a DMA channel.
netvista\providerappenddma.htm
netvista
05/02/2018
DMA_APPEND_HANDLER callback function
DMA_APPEND_HANDLER, DMA_APPEND_HANDLER callback, ProviderAppendDma, ProviderAppendDma callback function [Network Drivers Starting with Windows Vista], netdma/ProviderAppendDma, netdma_ref_ce5895a2-ac0c-4b98-98be-9f95edf091d3.xml, netvista.providerappenddma
netdma.h
Netdma.h
Windows
Supported for NetDMA 2.0 drivers in Windows Server 2008. Supported for NetDMA 1.1 drivers in Windows Server 2008. Supported for NetDMA 1.0 drivers in Windows Server 2008 and Windows Vista.
<= DISPATCH_LEVEL
Windows
DMA_APPEND_HANDLER
netdma/DMA_APPEND_HANDLER
APIRef
kbSyntax
UserDefined
netdma.h
DMA_APPEND_HANDLER

DMA_APPEND_HANDLER callback function

-description

Note  The NetDMA interface is not supported in Windows 8 and later.

The ProviderAppendDma function appends a linked list of DMA descriptors to the last descriptor on a DMA channel.

-parameters

-param ProviderChannelContext [in]

A pointer that identifies a DMA channel's context area. The DMA provider returned this handle to NetDMA at the location that is specified in the pProviderChannelContext parameter of the ProviderAllocateDmaChannel function.

-param DescriptorVirtualAddress [in]

A pointer to the virtual address of the first NET_DMA_DESCRIPTOR structure in a linked list of DMA descriptors. The corresponding physical address is specified at the DescriptorPhysicalAddress parameter.

-param DescriptorPhysicalAddress [in]

A pointer to the physical address of the first DMA descriptor in a linked list of DMA descriptors. The corresponding virtual address is specified at the DescriptorVirtualAddress parameter.

-param DescriptorCount [in]

The number of DMA descriptors at DescriptorVirtualAddress .

Note  NetDMA provider drivers prior to NetDMA version 2.0 can ignore the DescriptorCount parameter. For NetDMA 2.0 and later versions, this parameter is the count of descriptors in the DMA operation.
 

-returns

ProviderAppendDma returns one of the following status values:

Return code Description
STATUS_SUCCESS
 The operation completed successfully.
STATUS_UNSUCCESSFUL
 The operation failed for unspecified reasons.

-remarks

The NetDMA interface calls a DMA provider driver's ProviderAppendDma function to append a linked list of DMA descriptors after the last descriptor on a DMA channel. The NetDMA interface can call ProviderAppendDma any number of times after a DMA transfer is started. However, the NetDMA interface must call the ProviderStartDma function after a channel reset or abort, or after the DMA channel is first allocated.

Note  In NetDMA 2.0 and later versions, the linked list of descriptors is not NULL-terminated. The NextDescriptor member in the last descriptor in the linked list specifies the physical address of the NET_DMA_DESCRIPTOR structure that will be used in the subsequent call to the ProviderAppendDma function. A NetDMA 2.0 provider driver can cache the address in NextDescriptor and use this address as the beginning of the linked list for the next Append operation.
 
The NetDMA interface sets the NextDescriptor member of the last descriptor to the beginning of the new chain of descriptors before calling ProviderAppendDma.

If the current descriptor in an active transfer is the last descriptor, the DMA engine must reread the last descriptor. The NextDescriptor member in the last NET_DMA_DESCRIPTOR structure should have a new address, and the DMA engine should continue with the next descriptor. If the current descriptor is not the last descriptor, the DMA engine can continue processing DMA descriptors with no additional tasks.

NetDMA calls ProviderAppendDma at IRQL <= DISPATCH_LEVEL.

-see-also

NET_DMA_DESCRIPTOR

ProviderAllocateDmaChannel

ProviderStartDma