/**
  Connects all drivers to all controllers.
  This function make sure all the current system driver will manage
  the correspoinding controllers if have. And at the same time, make
  sure all the system controllers have driver to manage it if have.

**/
VOID
EFIAPI
BdsLibConnectAllDriversToAllControllers (
  VOID
  )
{
  EFI_STATUS  Status;

  do {
    //
    // Connect All EFI 1.10 drivers following EFI 1.10 algorithm
    //
    BdsLibConnectAllEfi ();

    //
    // Check to see if it's possible to dispatch an more DXE drivers.
    // The BdsLibConnectAllEfi () may have made new DXE drivers show up.
    // If anything is Dispatched Status == EFI_SUCCESS and we will try
    // the connect again.
    //
    Status = gDS->Dispatch ();

  } while (!EFI_ERROR (Status));

}

将系统中已有的UEFI 驱动连接到对应的设备

 Status = gDS->Dispatch()

调用Dispatch运行曾经因为依赖关系不满足无法运行的驱动。

/**
  This function will connect all current system handles recursively. 
  
  gBS->ConnectController() service is invoked for each handle exist in system handler buffer.
  If the handle is bus type handler, all childrens also will be connected recursively
  by gBS->ConnectController().

  @retval EFI_SUCCESS           All handles and it's child handle have been connected
  @retval EFI_STATUS            Error status returned by of gBS->LocateHandleBuffer().

**/
EFI_STATUS
EFIAPI
BdsLibConnectAllEfi (
  VOID
  )
{
  EFI_STATUS  Status;
  UINTN       HandleCount;
  EFI_HANDLE  *HandleBuffer;
  UINTN       Index;

  Status = gBS->LocateHandleBuffer (
                  AllHandles,
                  NULL,
                  NULL,
                  &HandleCount,
                  &HandleBuffer
                  );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  for (Index = 0; Index < HandleCount; Index++) {
    Status = gBS->ConnectController (HandleBuffer[Index], NULL, NULL, TRUE);
  }

  if (HandleBuffer != NULL) {
    FreePool (HandleBuffer);
  }

  return EFI_SUCCESS;
}
 

枚举系统中所有的句柄，包括设备句柄和Image 句柄。

对每一个句柄，调用 ConnectController 进行递归连接。对于非设备句柄，

ConnectController 会直接返回EFI_INVALID_PARAMETER.

断开所有设备

/**
  This function will disconnect all current system handles. 
  
  gBS->DisconnectController() is invoked for each handle exists in system handle buffer.
  If handle is a bus type handle, all childrens also are disconnected recursively by
  gBS->DisconnectController().

  @retval EFI_SUCCESS           All handles have been disconnected
  @retval EFI_STATUS            Error status returned by of gBS->LocateHandleBuffer().

**/
EFI_STATUS
EFIAPI
BdsLibDisconnectAllEfi (
  VOID
  )
{
  EFI_STATUS  Status;
  UINTN       HandleCount;
  EFI_HANDLE  *HandleBuffer;
  UINTN       Index;

  //
  // Disconnect all
  //
  Status = gBS->LocateHandleBuffer (
                  AllHandles,
                  NULL,
                  NULL,
                  &HandleCount,
                  &HandleBuffer
                  );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  for (Index = 0; Index < HandleCount; Index++) {
    Status = gBS->DisconnectController (HandleBuffer[Index], NULL, NULL);
  }

  if (HandleBuffer != NULL) {
    FreePool (HandleBuffer);
  }

  return EFI_SUCCESS;
}

枚举系统所有的句柄，包括设备句柄和Image 句柄。