Re: Problem in EFI_BOOT_SERVICES.OpenProtocol()

[Andrew Fish <afish@apple.com>]

> On Jun 1, 2017, at 10:37 AM, Amit kumar <akamit91@hotmail.com> wrote:
> 
> Hello Andrew,
> 
> Thanks for quick reply and acknowledging my query.
> 

Please file a bugzilla against the code. 

Thanks,

Andrew Fish

> Amit   
> From: afish@apple.com <mailto:afish@apple.com> <afish@apple.com <mailto:afish@apple.com>> on behalf of Andrew Fish <afish@apple.com <mailto:afish@apple.com>>
> Sent: Thursday, June 1, 2017 10:59:03 PM
> To: Amit kumar
> Cc: edk2-devel@lists.01.org <mailto:edk2-devel@lists.01.org>
> Subject: Re: [edk2] Problem in EFI_BOOT_SERVICES.OpenProtocol()
>  
> 
> > On Jun 1, 2017, at 10:13 AM, Amit kumar <akamit91@hotmail.com <mailto:akamit91@hotmail.com>> wrote:
> > 
> > Hello Andrew,
> > 
> > As per UEFI Spec EFI_ALREADY_STARTED is treated as error code, thus PciIo (The Interface 3rd parameter ) should remain NULL.
> > But after    OpenProtocol call even though Status = EFI_ALREADY_STARTED PciIo (The Interface 3rd parameter ) is getting modified and it not NULL anymore.
> > Is this not a problem ?
> > 
> 
> Amit,
> 
> I agree it looks like the code will fill in the Interface and return EFI_ALREADY_STARTED. And that does seem to conflict with the section of the spec you quote. Good catch. 
> 
> https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Dxe/Hand/Handle.c#L1097 <https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Dxe/Hand/Handle.c#L1097>
>   //
>   // This is the protocol interface entry for this protocol
>   //
>   if (Attributes != EFI_OPEN_PROTOCOL_TEST_PROTOCOL) {
>     *Interface = Prot->Interface;
>   }
>   Status = EFI_SUCCESS;
> 
>   ByDriver        = FALSE;
>   Exclusive       = FALSE;
>   for ( Link = Prot->OpenList.ForwardLink; Link != &Prot->OpenList; Link = Link->ForwardLink) {
>     OpenData = CR (Link, OPEN_PROTOCOL_DATA, Link, OPEN_PROTOCOL_DATA_SIGNATURE);
>     ExactMatch =  (BOOLEAN)((OpenData->AgentHandle == ImageHandle) &&
>                             (OpenData->Attributes == Attributes)  &&
>                             (OpenData->ControllerHandle == ControllerHandle));
>     if ((OpenData->Attributes & EFI_OPEN_PROTOCOL_BY_DRIVER) != 0) {
>       ByDriver = TRUE;
>       if (ExactMatch) {
>         Status = EFI_ALREADY_STARTED;
>         goto Done;
>       }
>     }
>     if ((OpenData->Attributes & EFI_OPEN_PROTOCOL_EXCLUSIVE) != 0) {
>       Exclusive = TRUE;
>     } else if (ExactMatch) {
>       OpenData->OpenCount++;
>       Status = EFI_SUCCESS;
>       goto Done;
>     }
>   }
> 
> Thanks,
> 
> Andrew Fish
> 
> > Status = gBS->OpenProtocol (
> >                  Controller,
> >                  &gEfiPciIoProtocolGuid,
> >                  (VOID **) &PciIo,
> >                  This->DriverBindingHandle,
> >                  Controller,
> >                  EFI_OPEN_PROTOCOL_BY_DRIVER
> >                  );
> > 
> > ________________________________
> > From: afish@apple.com <mailto:afish@apple.com> <afish@apple.com <mailto:afish@apple.com>> on behalf of Andrew Fish <afish@apple.com <mailto:afish@apple.com>>
> > Sent: Thursday, June 1, 2017 10:28:16 PM
> > To: Amit kumar
> > Cc: edk2-devel@lists.01.org <mailto:edk2-devel@lists.01.org>
> > Subject: Re: [edk2] Problem in EFI_BOOT_SERVICES.OpenProtocol()
> > 
> > 
> >> On Jun 1, 2017, at 9:46 AM, Amit kumar <akamit91@hotmail.com <mailto:akamit91@hotmail.com>> wrote:
> >> 
> >> Hi,
> >> I am trying to open PciIoProtocol and facing some issue.
> >> 
> >> below is the code
> >> 
> >> EFI_PCI_IO_PROTOCOL *PciIo=NULL;
> >> EFI_STATUS                      Status;
> >> 
> >> Status = gBS->OpenProtocol (
> >>                 Controller,
> >>                 &gEfiPciIoProtocolGuid,
> >>                 (VOID **) &PciIo,
> >>                 This->DriverBindingHandle,
> >>                 Controller,
> >>                 EFI_OPEN_PROTOCOL_BY_DRIVER
> >>                 );
> >> 
> >> it returns Status = EFI_ALREADY_STARTED, but PciIo is not NULL.
> >> Is it not supposed to return PciIo as NULL ?
> >> As per UEFI 2.6 Spec Section 6.3 page 182.
> >> 
> > 
> > Amit,
> > 
> > Look at the Status Codes Returned section at the end of that section.
> > 
> > Attributes is BY_DRIVER and there is an item on the open list with an attribute of BY_DRIVER whose agent handle is the same as AgentHandle.
> > 
> > Attributes is BY_DRIVER|EXCLUSIVE and there is an item on the open list with an attribute of BY_DRIVER|EXCLUSIVE whose agent handle is the same as AgentHandle.
> > 
> > Thanks,
> > 
> > Andrew Fish
> > 
> >> There are a number of reasons that this function call can return an error. If an error is returned, then
> >> AgentHandle, ControllerHandle, and Attributes are not added to the list of agents
> >> consuming the protocol interface specified by Handle and Protocol, and Interface is
> >> returned unmodified.
> >> 
> >> Thanks And Regards
> >> Amit
> >> _______________________________________________
> >> edk2-devel mailing list
> >> edk2-devel@lists.01.org <mailto:edk2-devel@lists.01.org>
> >> https://lists.01.org/mailman/listinfo/edk2-devel <https://lists.01.org/mailman/listinfo/edk2-devel>
> > 
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