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FN_VMB_CHANNEL_CREATE_GPADL_FROM_BUFFER callback function (vmbuskernelmodeclientlibapi.h)

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The VmbChannelCreateGpadlFromBuffer function creates a Guest Physical Address Descriptor List (GPADL) that describes a client-side buffer. The GPADL can be used in the server to access the buffer.

Syntax

FN_VMB_CHANNEL_CREATE_GPADL_FROM_BUFFER FnVmbChannelCreateGpadlFromBuffer;

NTSTATUS FnVmbChannelCreateGpadlFromBuffer(
  VMBCHANNEL Channel,
  UINT32 Flags,
  PVOID Buffer,
  UINT32 ByteCount,
  PUINT32 GpadlHandle
)
{...}

Parameters

Channel

A handle for a channel.

Flags

Flags. The possible values are the following:

Value Meaning
VMBUS_CHANNEL_GPADL_READ_ONLY
 If you specify this value, the buffer is read-only. Otherwise, the server can write to the buffer. This is not a security measure, but can improve snapshot and live migration performance.

Buffer

The buffer, which is probed and locked until the GPADL is torn down.

ByteCount

The length of the buffer, in bytes.

GpadlHandle

A GPADL handle of the created Memory Descriptor List (MDL). Send this to the server to use with the VmbChannelMapGpadl function.

Return value

Returns STATUS_SUCCESS if the operation succeeds, or an appropriate NTSTATUS error code otherwise.

Remarks

When this function returns, the server endpoint can call VmbChannelMapGpadl, because VMBus will already have sent the GPADL description to the opposite endpoint and received confirmation.

The GPADL must be deleted by using the VmbChannelDeleteGpadl function.

Important

This function is called through the VMBus Kernel Mode Client Library (KMCL) interface, provided by the Vmbkmcl.sys bus driver. This is a client function accessed from the KMCL_CLIENT_INTERFACE_V1 structure.

For more information, see the Remarks section of the KMCL_CLIENT_INTERFACE_V1.

Requirements

Requirement Value
Minimum supported client Windows 10, version 1803
Header vmbuskernelmodeclientlibapi.h

See also

VmbChannelDeleteGpadl

VmbChannelMapGpadl