Re: OpenProtocol() giving me EFI_INVALID_PARAMETER


Andrew Fish
 

On Jul 17, 2021, at 9:41 AM, Ethin Probst <harlydavidsen@gmail.com> wrote:

Hey all,

So my UsbAudio.efi app has hit a bit of a roadblock. This code:

```C
status = st->BootServices->OpenProtocol(handles[i],
&gEfiUsbIoProtocolGuid, (void**)&UsbIo, imageHandle, NULL,
EFI_OPEN_PROTOCOL_EXCLUSIVE);
if (EFI_ERROR(status)) {
Print(L"%r, skipping\n", status);
continue;
}
```
How are you constructing handle[]? Could it have gotten stale? You could print out the value of handle[I] on the failure.

The contents of a handle are not defined, but the current implementation is a pointer to an IHANDLE internal data structure in the DXE Core. If you are at the UEFI Shell and you `dh -v <handleNum> it will show the <handleNum> and the value.

Shell> dh -v 98
98: 6d5CF18
….

I think you can `dh -p UsbIo’ to get the list of the UsbIo handles.

So you can poke around and see what is happening on that handle.

I guess the handle[] array could be getting corrupted? So you could check for that?

Thanks,

Andrew Fish

Is giving me EFI_INVALID_PARAMETER and I don’t know why. I don't think
I'm violating any of its constraints, according to the specification,
and I haven't touched this code since it was written. It also happens
irregularly: sometimes it happens on the USB audio streaming device,
or if I have a device plugged in it might happen on that device, you
get the idea. But it doesn't consistently fail. Does anybody have any
idea what's going on?

--
Signed,
Ethin D. Probst

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