Re: Can't open PciIo protocol in both qemu (Nt32Pkg) and VirtualBox EFI

[Laszlo Ersek <lersek@redhat.com>]

On 10/26/17 00:20, Nikolay Bodunov wrote:
> 
> Hello
> 
> I try to make work a code from "UEFI Driver Writer Guide", but always receive EFI_UNSUPPORTED status:
> 
> EFI_STATUS
> EFIAPI
> PciDriverOnlyDriverBindingSupported (
>   IN EFI_DRIVER_BINDING_PROTOCOL  *This,
>   IN EFI_HANDLE                   ControllerHandle,
>   IN EFI_DEVICE_PATH_PROTOCOL     *RemainingDevicePath OPTIONAL
>   )
> {
>     EFI_STATUS                       Status;
>     EFI_PCI_IO_PROTOCOL        *PciIo;
>     Status = gBS->OpenProtocol (
>         ControllerHandle,
>         &gEfiPciIoProtocolGuid,
>         (VOID **)&PciIo,
>         This->DriverBindingHandle,
>         ControllerHandle,
>         EFI_OPEN_PROTOCOL_BY_DRIVER 
>         );
>     DEBUG((EFI_D_INFO, "Status is %r \r\n", Status));
>     if (EFI_ERROR (Status)) {
>         return Status;
>     }
>     return EFI_SUCCESS;
> }
> 
> However, for example, with EFI_SIMPLE_FILE_SYSTEM_PROTOCOL instead of  EFI_PCI_IO_PROTOCOL  OpenProtocol() works fine and returns EFI_SUCCESS.
> 
> Driver project was created with UEFI Driver Wizard. Inf file contains gEfiPciIoProtocolGuid.
> Where I could make a mistake?

There's no mistake, it just means that the ControllerHandle passed to
the function does not support the PciIo interface.

Please read "Driver Writer’s Guide for UEFI 2.3.1", sections:
- 6   UEFI Driver Categories
- 7.2 UEFI Driver Model
- 18  PCI Driver Design Guidelines

https://github.com/tianocore/tianocore.github.io/wiki/UEFI-Driver-Writer%27s-Guide

Thanks
Laszlo