Comment 12 for bug 383240

The upstream configure script doesn't currently seem to work this way for any of the ARM extensions. Instead, you seem need to build with the right --extra-cflags as well as enabling the extension(s) you want, such as --enable-armvfp or --enable-neon.

The configure script has the facilities to add cflags in this way though; it's used for the ultraspac vis extension (whatever that is); but I don't know what the upstream community prefers.

In addition to the above, it looks like -march=armv7-a should also be added to extra-cflags when building the NEON flavour; otherwise the ffmpeg configuration assumes that the PLD (cache preload) instruction can't be used because the baseline build architecture is armv5. But it doesn't really make sense to assume that any ARMv7 features may be absent if NEON is present.

This would give --extra-cflags='-march=armv7-a -mfpu=neon -mfloat-abi=softfp' for the neon flavour.

I'll point Måns at this thread and ask for his comments.