Re: [edk2-devel] [PATCH 1/3] UsbNetworkPkg/UsbRndis: Add USB RNDIS devices support

["RichardHo [何明忠]" <richardho@ami.com>]

Hi Michael,

Thanks for your response. We will do more test in Nic->CanReceive flag's code next.

Thanks,
Richard

-----Original Message-----
From: Michael Brown <mcb30@ipxe.org>
Sent: 2023年1月11日 9:18 AM
To: devel@edk2.groups.io; Richard Ho (何明忠) <RichardHo@ami.com>
Cc: Andrew Fish <afish@apple.com>; Leif Lindholm <quic_llindhol@quicinc.com>; Michael D Kinney <michael.d.kinney@intel.com>; Michael Kubacki <michael.kubacki@microsoft.com>; Zhiguang Liu <zhiguang.liu@intel.com>; Liming Gao <gaoliming@byosoft.com.cn>; Tony Lo (羅金松) <TonyLo@ami.com>
Subject: [EXTERNAL] Re: [edk2-devel] [PATCH 1/3] UsbNetworkPkg/UsbRndis: Add USB RNDIS devices support


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On 08/12/2022 03:44, RichardHo [何明忠] via groups.io wrote:
> +    case PXE_OPFLAGS_RECEIVE_FILTER_DISABLE:
> +      if (Cdb->CPBsize != PXE_CPBSIZE_NOT_USED) {
> +        Cdb->StatFlags = PXE_STATFLAGS_COMMAND_FAILED;
> +        Cdb->StatCode  = PXE_STATCODE_INVALID_CDB;
> +      }
> +
> +      Nic->CanReceive = TRUE;
> +      break;

This seems to be the only point in the entire driver that ever sets CanReceive = TRUE.

The result of this is that the device will be unable to receive unless at least one attempt has been made to *disable* the receive filters.
This seems unlikely to be the intended behaviour.

It so happens that the combination of MnpDxe and SnpDxe usually *does* make an attempt to disable the receive filters, and so the bug is masked in normal operation.

I have added a workaround for this bug to iPXE:

   https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fipxe%2Fipxe%2Fcommit%2Fab1954638&data=05%7C01%7Crichardho%40ami.com%7C0fa15caf7eb249a0400708daf371adc1%7C27e97857e15f486cb58e86c2b3040f93%7C1%7C0%7C638089966820616004%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=MCb2cgKhHMXGvGNB9uSaJbDHwRo3wr8zr5oJizuRuOU%3D&reserved=0

I would suggest fixing your UndiReceiveFilter() function so that the workaround is not necessary.  I cannot follow the logic behind the CanReceive flag, so I am unable to suggest a patch, sorry.

Thanks,

Michael

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