Re: [Discuss-gnuradio] Problem compiling on "Raspbian wheezy".

It's still detecting and attempting to compile NEON vector instructions in gr-filter; there are NEON assembly routines in there intended to speed up E100 filter operations. I don't know what string CMake should be checking for there, but "arm" is inappropriate, since it makes no attempt to determine if the ARM has NEON support or not. We should probably write a "FindNeon.cmake" to set this more appropriately.

In the meantime, you can cut out that entire section of filter stuff starting at gnuradio-core/src/lib/filter/CMakeLists.txt line 212.

--n

On Thu, Jul 19, 2012 at 10:36 PM, Andrew Back <andrew@carrierdetect.com> wrote:

On 19 July 2012 18:06, Nick Foster <nick@ettus.com> wrote:
> The --mfpu=neon flag is inappropriate for Raspberry Pi, which lacks NEON. I
> suspect Gnuradio's build system is detecting ARM and assuming NEON exists. I
> know gr-filter is doing this (see
> gnuradio/gnuradio-core/src/lib/filter/CMakeLists.txt line 212).
>
> Some rudimentary checking for NEON is probably appropriate. Volk is already
> doing this, although its checks are at runtime so they look a little
> different than a CMake script would.

So I found [1] what appears to be the correct flags and set these:

cmake -DCMAKE_CXX_FLAGS:STRING="-march=armv6 -mfpu=vfp
-mfloat-abi=hard" -DCMAKE_C_FLAGS:STRING="-march=armv6 -mfpu=vfp
-mfloat-abi=hard" ../

But now the build fails even earlier with gnuradio-core:

[ 17%] Building CXX object
gnuradio-core/src/lib/CMakeFiles/gnuradio-core.dir/filter/gr_fir_fff_armv7_a.cc.o
[ 17%] Building C object
gnuradio-core/src/lib/CMakeFiles/gnuradio-core.dir/filter/dotprod_fff_armv7_a.c.o
/tmp/ccHDAfuu.s: Assembler messages:
/tmp/ccHDAfuu.s:26: Error: selected FPU does not support instruction
-- `vmov.f32 q8,#0.0'
/tmp/ccHDAfuu.s:27: Error: selected FPU does not support instruction
-- `vmov.f32 q9,#0.0'
/tmp/ccHDAfuu.s:30: Error: selected processor does not support ARM
mode `vld1.32 {d0,d1,d2,d3},[r0]!'
/tmp/ccHDAfuu.s:31: Error: selected processor does not support ARM
mode `vld1.32 {d4,d5,d6,d7},[r1]!'
/tmp/ccHDAfuu.s:32: Error: selected FPU does not support instruction
-- `vmla.f32 q8,q0,q2'
/tmp/ccHDAfuu.s:33: Error: selected FPU does not support instruction
-- `vmla.f32 q9,q1,q3'
/tmp/ccHDAfuu.s:35: Error: selected FPU does not support instruction
-- `vadd.f32 q8,q8,q9'
/tmp/ccHDAfuu.s:36: Error: selected processor does not support ARM
mode `vpadd.f32 d0,d16,d17'
make[2]: *** [gnuradio-core/src/lib/CMakeFiles/gnuradio-core.dir/filter/dotprod_fff_armv7_a.c.o]
Error 1
make[1]: *** [gnuradio-core/src/lib/CMakeFiles/gnuradio-core.dir/all] Error 2

make: *** [all] Error 2

Which IIRC is around where it was failing when I did not set any flags
at all with Cmake.

Regards,

Andrew

[1] http://www.raspbian.org/RaspbianFAQ#What_compilation_options_should_be_set_Raspbian_code.3F

--
Andrew Back
http://carrierdetect.com