How can I to transmit at least a “couple of bytes” on the local network (UEFI DXE)

问题

I need to write driver (DXE), that can transmit "couple of bytes" from virtual machine (QEMU) to the host system (OS - Ubuntu). I've read the UEFI_Spec and Guide for developers, but I still don't understand, how to write the code and what protocol should I use (tried to use TCPv4 but can't even LocateHandleBuffer).

EFI_STATUS Status = gBS->LocateHandleBuffer(ByProtocol, &gEfiTcp4ProtocolGuid, NULL, &HandleCount, &HandleBuffer);

I get:

EFI_UNSUPPORTED

If somebody can explain me or can show examples of the code, I'll be very grateful. Thanks.

回答1:

For most network related protocols you first have to use the corresponding "Service Binding Protocol" to get a handle which contains the protocol you are looking for.

Use this steps to access the Tcp4Protocol:

gBS->LocateHandleBuffer(ByProtovol,gEfiTcp4ServiceBindingProtocolGuid, NULL, &HandleCount, &HandleBuffer);
// Loop over the HandleBuffer Array and pick the one you need
gBS->HandleProtocol(HandleBuffer[YourIndex], &gEfiTcp4ServiceBindingProtocolGuid, &Tcp4SBProtocol);
Tcp4SBProtocol->CreateChild(Tcp4SBProtocol, &Tcp4Handle);
gBS->HandleProtocol(Tcp4Handle, &gEfiTcp4ProtocolGuid, &Tcp4Protocol);

To check if a NIC is available you can use:

// This should return EFI_SUCCESS
gBS->LocateProtocol(&gEfiSimpleNetworkProtocolGuid, NULL, &SimpleNetworkProtocol);

There is a complete code sample for the HttpProtocol inside the Uefi specification (starting at page 1548), the Tcp4Protocol is not very different.

来源：https://stackoverflow.com/questions/60246528/how-can-i-to-transmit-at-least-a-couple-of-bytes-on-the-local-network-uefi-dx

标签

networking

driver

uEFI