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From: Michael Zimmermann <sigmaepsilon92@gmail.com>
Date: Sat, 12 May 2018 23:11:09 +0200
Message-ID: <CAN9vWDKOco6V3qD7+6K4SrCNpS2Gi6yn-sh5hc4V7XXNFnRm9w@mail.gmail.com>
To: edk2-devel-01 <edk2-devel@lists.01.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>,
 Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: reasoning beehind prohibiting VFP/NEON on AArch32
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For AArch32 the spec says in 2.3.5.3:
> Floating point, SIMD, vector operations and other instruction set
extensions must not
be used.

For AArch64 the spec says in 2.3.6.4:
> Floating point and SIMD instructions may be used.

So is there a reason why AArch32 is not allowed to use Floating point
operations?
I'd understand if this restriction was limited to runtime services only but
I don't see how it makes sense for boot services.

I've written a patch which adds NEON support to FrameBufferBltLib to
increase the rendering performance(by a lot actually) for 24bit displays
and thought about sending it to the mailing list - that's why the question
came up.

Thanks
Michael