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From: Leif Lindholm <leif.lindholm@linaro.org>
To: "Kinney, Michael D" <michael.d.kinney@intel.com>,
	"Gao, Liming" <liming.gao@intel.com>,
	Laszlo Ersek <lersek@redhat.com>
Cc: "edk2-devel@lists.01.org" <edk2-devel@lists.01.org>
Subject: Re: [PATCH] MdePkg: add big-endian MMIO BaseBeIoLib
Date: Tue, 17 Apr 2018 14:26:49 +0100	[thread overview]
Message-ID: <20180417132649.wv7ql7xxfezzhxsl@bivouac.eciton.net> (raw)
In-Reply-To: <09cc135a-c3b7-bcbd-1a71-6454e3ba7623@redhat.com>

On Mon, Apr 16, 2018 at 10:42:26PM +0200, Laszlo Ersek wrote:
> 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.

Yes. I'm thinking that is a good enough solution for this type of
situation and I overcomplicated things. Apologies for that.

We are talking about the relatively unusual situation where an
otherwise driver-compatible device can in some platforms be of a
different endianness than in others.

So, Mike, Liming - would you be OK with a solution similar to
https://www.mail-archive.com/edk2-devel@lists.01.org/msg36520.html.

/
    Leif


  parent reply	other threads:[~2018-04-17 13:26 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-13 17:42 [PATCH] MdePkg: add big-endian MMIO BaseBeIoLib Leif Lindholm
2018-04-13 19:24 ` Kinney, Michael D
2018-04-13 19:31   ` Leif Lindholm
2018-04-13 23:32     ` Kinney, Michael D
2018-04-16 10:07       ` Leif Lindholm
2018-04-16 14:10         ` Kinney, Michael D
2018-04-16 14:34           ` Michael Brown
2018-04-16 20:42             ` Laszlo Ersek
2018-04-16 22:14               ` Michael Brown
2018-04-17  8:01                 ` Laszlo Ersek
2018-04-17  8:24                   ` Michael Brown
2018-04-17  9:57                     ` Laszlo Ersek
2018-04-17 13:26               ` Leif Lindholm [this message]
2018-04-17 15:20                 ` Kinney, Michael D
2018-04-17  6:57           ` Udit Kumar
2018-04-16 19:32         ` Laszlo Ersek
2018-04-17  8:15           ` Udit Kumar
2018-04-17  9:42             ` Laszlo Ersek
2018-04-17 10:32               ` Udit Kumar
2018-04-17 13:55           ` (spawning off more style discussion) Leif Lindholm
2018-04-18  8:51             ` Laszlo Ersek
2018-04-16  4:39 ` [PATCH] MdePkg: add big-endian MMIO BaseBeIoLib Udit Kumar

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