From: Arnout Vandecappelle <arnout@mind.be>
To: buildroot@busybox.net
Subject: [Buildroot] [PATCH] mplayer: fix compilation of NEON assembly in libavcodec
Date: Tue, 09 Oct 2012 23:29:39 +0200 [thread overview]
Message-ID: <50749743.5010700@mind.be> (raw)
In-Reply-To: <87pq4s3e0t.fsf@macbook.be.48ers.dk>
On 08/10/12 22:27, Peter Korsgaard wrote:
> Arnout> +diff -Nrup mplayer-1.1.orig/configure mplayer-1.1/configure
> Arnout> +--- mplayer-1.1.orig/configure 2012-10-06 00:31:57.706985824 +0200
> Arnout> ++++ mplayer-1.1/configure 2012-10-06 00:49:32.618948116 +0200
> Arnout> +@@ -2935,6 +2935,9 @@ if arm ; then
> Arnout> + inline_asm_check '"vadd.i16 q0, q0, q0"'&& neon=yes
> Arnout> + fi
> Arnout> + echores "$neon"
> Arnout> ++ if test $neon = "yes" ; then
> Arnout> ++ extra_cflags="$extra_cflags -mfpu=neon -mfloat-abi=softfp"
>
> Why softfp? Is that just an optimization or is it needed? How does that
> work with a hardfp toolchain/libraries?
>
> Please document why this is needed (if it is) in the commit message and
> resubmit, thanks.
neon fpu (like vfp* fpu) can only be used with the softfp abi, so both are
needed. This is kind of standard ARM knowledge :-) Admittedly, it's silly
of gcc that it doesn't automatically set the float-abi to the only supported
one...
Toolchains that hardcode -mfloat-abi=hard cannot have neon instructions,
I suppose. I haven't tested it though.
I also don't know what happens with an external toolchain that has
BR2_VFP_FLOAT set, because that option adds an -mfpu=vfp to the toolchain
command line.
Regards,
Arnout
--
Arnout Vandecappelle arnout at mind be
Senior Embedded Software Architect +32-16-286540
Essensium/Mind http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint: 7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F
next prev parent reply other threads:[~2012-10-09 21:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-05 23:03 [Buildroot] [PATCH] mplayer: fix compilation of NEON assembly in libavcodec Arnout Vandecappelle
2012-10-05 23:45 ` Sagaert Johan
2012-10-08 20:27 ` Peter Korsgaard
2012-10-09 21:29 ` Arnout Vandecappelle [this message]
2012-10-10 9:13 ` Peter Korsgaard
2012-10-15 6:53 ` Peter Korsgaard
2012-10-15 19:05 ` Arnout Vandecappelle
2012-10-15 20:49 ` Arnout Vandecappelle
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