Comment 6 for bug 524859

Dave Martin (dave-martin-arm) wrote :

Patch to avoid building everything with -mfpu=neon, and enable HWCAP-based runtime detection of NEON.

This should give us binaries which work across our ARMv7 targets, and which doesn't use NEON code where inappropriate (Dove / Babbage2/1)

This patch applies against upstream and against lucid x264 (2:0.85.1442.1+git781d30-1).
This patch should work for debian (it should not cause NEON to be enabled where it previously was not).

Upstream might not be so happy about:

  * the --disable-assume-neon configure arg. There might be a better way to enable NEON only in the asm, but this was my best idea at the moment.

  * Disabling of the "fast NEON MRC" test. This performance counter based test may not be safe across all platforms, and won't reliably give the right answer even where it doesn't SIGILL— it also requires a patched kernel; so we probably don't want it enabled in Ubuntu (unless we can use some other decision route like identifying the CPU from the contents of /proc/cpuinfo. I haven't attempted this for now.)

See the next patch for proposed changes to debian/rules.