On 11/10/2017 06:41 AM, Philip Balister via USRP-users wrote: > On 11/10/2017 04:11 AM, Ron Economos via USRP-users wrote: >> I guess this is a little late, but you can pass in compiler flags on the >> command line with -DCMAKE_CXX_FLAGS. For example: >> >> cmake -DCMAKE_CXX_FLAGS:STRING="-mfloat-abi=hard -mfpu=neon >> -mtune=cortex-a15" ../ > > That would be the preferred way. The patch mentioned assumes that > anytime you are using a compiler with the neon.h header file, the SoC > you are compiling for has a neon unit. This is a bad assumption. There > are a few examples of SoC's around that do not have a neon unit. Now UHD > will generate neon and create runtime failures. > > Bottom line, in the ARM world, you cannot test compiler features to > figure out what features the runtime system has.
Also, another quick look suggests neon for aarch64 is no longer built. Philip > > Philip > > >> >> Ron >> >> On 11/10/2017 12:07 AM, Gwenhael Goavec-Merou via USRP-users wrote: >>> Hello, >>> >>> maybe this : https://github.com/EttusResearch/uhd/pull/135 >>> will help you >>> >>> Gwen >>> >>> On Fri, 10 Nov 2017 00:29:25 -0600 >>> Kevin McGuire via USRP-users <usrp-users@lists.ettus.com> wrote: >>> >>>> I was able to get the compiler flags passed in so that the check for >>>> the header arm_neon.h passes. I added it to the CMakeList root file >>>> with SET(CMAKE_CXX_FLAGS, "${CMAKE_CXX_FLAGS} -mfloat-abi=softfp >>>> -mfpu=neon"). >>>> >>>> Then, it would detect neon. However, I spent considerable time >>>> cleaning up whatever package problems I had since I ended up with a >>>> bunch of weird errors. >>>> >>>> Once I straightened my packages up (Debian), it is compiling with >>>> neon! And, hopefully, it will actually use the ARM neon routines. >>>> >>>> On Thu, Nov 9, 2017 at 3:22 AM, Kevin McGuire <kmcg3...@gmail.com> >>>> wrote: >>>> >>>>> I have noticed that neon support for the converter is not enabling. >>>>> The CMakeError.log has this output. I am not certain as I am not >>>>> really familiar with ARM and NEON, but I checked my CPU and it does >>>>> support it. Also, the error message below is saying it is just a >>>>> matter of passing certain flags. >>>>> >>>>> /mnt/extra/usr/lib/gcc/arm-linux-gnueabihf/4.8/include/arm_neon.h:32:2: >>>>> error: #error You must enable NEON instructions (e.g. >>>>> -mfloat-abi=softfp -mfpu=neon) to use arm_neon.h >>>>> #error You must enable NEON instructions (e.g. -mfloat-abi=softfp >>>>> -mfpu=neon) to use arm_neon.h >>>>> >>>>> Normally, I would just fix it myself and move forward, but me and >>>>> CMake mix like oil and water. It is kind of embarrassing but I >>>>> swear it never does what I want it do - such as adding a darn flag. >>>>> I even tried to force the options, lol, and all be danged if CMake >>>>> finds some way to error. >>>>> >>>>> Will work on this tomorrow, but if anyone has a solution I am all >>>>> ears. If not then no problem and I will reply when I figure it out. >>>>> >>>>> This came about when I noticed what really seemed like abnormally >>>>> high CPU usage on my ARM code for a simple shuffling of data out of >>>>> the network packets. I traced what I felt like was the biggest >>>>> possible hot spot to the converter routine. Anyway, that is my plan >>>>> right now, to see if NEON might help if the converter is having to >>>>> swap byte order. >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > _______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
