tags 594093 + patch confirmed
stop
On Wed, Aug 25, 2010, Riku Voipio wrote:
> Neither is it a toolchain bug nor do we have any NEON capable buildds.
It's ok, we don't need NEON capable buildds; this builds an alternate
set of ffmpeg libs for NEON (available via hwcaps).
> And, btw ubfx is not even a NEON instruction. It is a ARMv7 instruction.
It actually seems to have been added in armv6t2+ (even in ARM mode).
> The error is caused by debians toolchain default flags. you need to pass
> -march=armv7-a for the debian-neon pass to get armv7 instructions accepted.
Now the NEON flavor implies armv7-a, so that's what we should turn on.
Riku, Reinhard, I only checked the gcc tests in the attached debdiff,
but didn't do a full build under Debian; would you mind trying it out?
Now one thing which this patch does NOT do is turn on armv7-a for the
NEON flavour if the toolchain defaults to armv6t2, so we might be
missing some small optimizations, but I didn't check how to test for
armv7-a versus armv6t2. If ffmpeg relies on the some armv7-a-only
assembly, then we will quickly find out :-)
Thanks,
--
Loïc Minier
diff -u ffmpeg-0.6~svn20100505/debian/confflags
ffmpeg-0.6~svn20100505/debian/confflags
--- ffmpeg-0.6~svn20100505/debian/confflags
+++ ffmpeg-0.6~svn20100505/debian/confflags
@@ -33,11 +33,14 @@
has_vfp := $(call check_asm, $(vfp_asm))
neon_asm := vadd.i16 q0, q0, q0
has_neon := $(call check_asm, $(neon_asm))
+ v6t2_asm := ubfx r0, r0, 0, 1
+ has_v6t2 := $(call check_asm, $(v6t2_asm))
- # only build
+ # only build a VFP flavour if the toolchain doesn't enable VFP by default
ifneq ($(has_vfp),1)
FLAVORS += vfp
endif
+ # only build a NEON flavour if the toolchain doesn't enable NEON by default
ifneq ($(has_neon),1)
FLAVORS += neon
endif
@@ -161,6 +164,12 @@
# NB: NEON always implies v7+ and ffmpeg's NEON implementation requires VFP
neon_build_confflags += $(confflags)
neon_build_confflags += --shlibdir=/usr/lib/neon/vfp
+# the NEON pass now requires ubfx which was introduced in armv6t2; we need to
+# enable at least armv6t2 for the NEON pass to build, but NEON implies armv7-a
+# so pass armv7-a
+ifneq ($(has_v6t2),1)
+neon_build_confflags += --extra-cflags="-marmv7-a"
+endif
neon_build_confflags += --extra-cflags="-mfpu=neon -mfloat-abi=softfp -fPIC
-DPIC"
neon_build_confflags += --enable-shared
neon_build_confflags += --disable-static
diff -u ffmpeg-0.6~svn20100505/debian/changelog
ffmpeg-0.6~svn20100505/debian/changelog
--- ffmpeg-0.6~svn20100505/debian/changelog
+++ ffmpeg-0.6~svn20100505/debian/changelog
@@ -1,3 +1,12 @@
+ffmpeg (4:0.6~svn20100505-2) UNRELEASED; urgency=low
+
+ * debian/confflags: detect whether the toolchain supports armv6t2 ("ubfx")
+ by default as that's now needed for the NEON pass; if it's not enabled by
+ default, pass -marmv7-a in extra-cflags for the NEON pass since NEON
+ implies ARMv7; closes: #594093.
+
+ -- Loïc Minier <loic.min...@linaro.org> Wed, 25 Aug 2010 21:42:57 +0200
+
ffmpeg (4:0.6~svn20100505-1) experimental; urgency=low
* update to new upstream. Closes: #569727
