Re: [PATCH] MdePkg: add big-endian MMIO BaseBeIoLib

[Laszlo Ersek <lersek@redhat.com>]

On 04/16/18 16:34, Michael Brown wrote:
> On 16/04/18 15:10, Kinney, Michael D wrote:
>> I agree that the opposite use case is a BE CPU
>> needing a LE operation.
>>
>> I think we only need a single lib class and lib
>> Instance that does the byte swap and we should
>> not use Le or Be in any of the names of the class,
>> instance, or APIs.  Just "Swap".
> 
> I may have misunderstood, but wouldn't using "Swap" within the API names
> effectively encode knowledge of the endianness of the _build_ platform
> into the source code?  This would prevent the same source code being
> built for both little-endian and big-endian CPUs.

Under this scenario, all drivers meant to be portable to both byte
orders would have to:
- link against both IoLib and IoSwapLib,
- determine at device binding time, from CPU endianness and device
  endianness combined, whether swapping was needed for that device,
- call the IoLib or IoSwapLib APIs through wrapper functions, or
  function pointers.

Thanks,
Laszlo