Re: [PATCH edk2-platforms] Platform/AMD/OverdriveBoard: fix byte order of default MAC addresses

["Gao, Liming" <liming.gao@intel.com>]

If PCD is related to one structure in DEC/DSC, it can be refer as structure pointer in C source code. Here is wiki for its usage: https://github.com/lgao4/edk2/wiki/StrucutrePcd-Usage

Thanks
Liming
>-----Original Message-----
>From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
>Andrew Fish via edk2-devel
>Sent: Tuesday, December 11, 2018 7:39 AM
>To: Leif Lindholm <leif.lindholm@linaro.org>
>Cc: edk2-devel@lists.01.org
>Subject: Re: [edk2] [PATCH edk2-platforms] Platform/AMD/OverdriveBoard:
>fix byte order of default MAC addresses
>
>
>
>> On Dec 10, 2018, at 3:33 PM, Leif Lindholm <leif.lindholm@linaro.org> wrote:
>>
>> On Mon, Dec 10, 2018 at 11:51:43PM +0100, Ard Biesheuvel wrote:
>>> On Mon, 10 Dec 2018 at 23:14, Leif Lindholm <leif.lindholm@linaro.org>
>wrote:
>>>>
>>>> On Wed, Dec 05, 2018 at 09:10:48PM +0100, Ard Biesheuvel wrote:
>>>>> The PCDs containing the default MAC addresses are of type UINT64,
>>>>> and so the byte order needs to be inverted. As they are currently,
>>>>> both default MAC addresses are invalid since they have the multicast
>>>>> bit set.
>>>>
>>>> Ah, oops.
>>>> That would also prevent them from being "locally administered" and
>>>> hence permissible without registering an entry in the OUI.
>>>>
>>>> However, to reduce someone interpreting the _new_ values that way
>>>> instead, could you do one of:
>>>> - Adding a comment explaining these are in reverse byte order.
>>>> or
>>>> - Convert them to the new Array type PCD[1], to make the bytes appear
>>>>  in natural order?
>>>>
>>>> [1] edk2 72a1d77694d51914c0dd6aa97dbfa58634b0a4a5
>>>
>>> How does one refer to such a PCD from C code?
>>
>> Good question :)
>>
>
>Seems like you would need cast the pointer to the data structure in the C
>code. If I understand correctly the change in the PCD creation code is you can
>now better structure the data, but it is no different on the consumer end and
>you got a blob of bytes in both cases.
>
>Thanks,
>
>Andrew Fish
>
>> /
>>    Leif
>>
>>>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>>> ---
>>>>> Platform/AMD/OverdriveBoard/OverdriveBoard.dsc | 4 ++--
>>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/Platform/AMD/OverdriveBoard/OverdriveBoard.dsc
>b/Platform/AMD/OverdriveBoard/OverdriveBoard.dsc
>>>>> index 05433d4472e8..2843e51f93f7 100644
>>>>> --- a/Platform/AMD/OverdriveBoard/OverdriveBoard.dsc
>>>>> +++ b/Platform/AMD/OverdriveBoard/OverdriveBoard.dsc
>>>>> @@ -469,8 +469,8 @@ DEFINE DO_CAPSULE   = FALSE
>>>>>   gAmdModulePkgTokenSpaceGuid.PcdPort1NetSpeed|1
>>>>>
>>>>> [PcdsDynamicDefault.common]
>>>>> -  gAmdStyxTokenSpaceGuid.PcdEthMacA|0x02A1A2A3A4A5
>>>>> -  gAmdStyxTokenSpaceGuid.PcdEthMacB|0x02B1B2B3B4B5
>>>>> +  gAmdStyxTokenSpaceGuid.PcdEthMacA|0xA5A4A3A2A102
>>>>> +  gAmdStyxTokenSpaceGuid.PcdEthMacB|0xB5B4B3B2B102
>>>>>
>>>>> [PcdsPatchableInModule]
>>>>>   gAmdModulePkgTokenSpaceGuid.PcdXgbeUseMacFromIscp|TRUE
>>>>> --
>>>>> 2.19.2
>>>>>
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