I'm also trying to compile for OSMC for RPi4.
I get this error when compiling x264 as part of tvheadend:
cd /home/osmc/tvheadend/tvheadend/build.linux/ffmpeg/x264-7ed753b10a61d0be95f683289dfb925b800b0676 && FFMPEG_PREFIX=/home/osmc/tvheadend/tvheadend/build.linux/ffmpeg/build/ffmpeg PKG_CONFIG=/home/osmc/tvheadend/tvheadend/support/pkg-config.ffmpeg ./configure --prefix=/ffmpeg --enable-static --disable-shared \
--extra-asflags="-DPIC" \
--extra-cflags="-fPIE" \
--disable-cli \
--disable-swscale \
--disable-lavf \
--disable-avs \
--disable-ffms \
--disable-gpac \
--disable-lsmash \
Unknown option --disable-shared, ignored
no NEON support, try adding -mfpu=neon to CFLAGS
If you really want to run on such a CPU, configure with --disable-asm.
make[1]: *** [Makefile.ffmpeg:233: /home/osmc/tvheadend/tvheadend/build.linux/ffmpeg/x264-7ed753b10a61d0be95f683289dfb925b800b0676/.tvh_build] Error 1
make[1]: Leaving directory '/home/osmc/tvheadend/tvheadend'
make: *** [Makefile:858: /home/osmc/tvheadend/tvheadend/build.linux/ffmpeg/build/ffmpeg/lib/libavcodec.a] Error 2
I modified the Makefile.ffmpeg and removed --disable-shared. Similar error, but without the warning.
Then, I tried to setup several CFLAGS and CXXFLAGS, using -mfpu=neon and others like:
export CFLAGS="-mcpu=cortex-a72 -mfloat-abi=hard -mfpu=neon-fp-armv8 -mtune=c
ortex-a72"
export CXXFLAGS="-mcpu=cortex-a72 -mfloat-abi=hard -mfpu=neon-fp-armv8 -mtune=c
ortex-a72"
It always fails the test:
osmc@osmc:~/tvheadend/tvheadend$ tail build.linux/ffmpeg/x264-7ed753b10a61d0be95f683289dfb925b800b0676/config.log
Failed commandline was:
--------------------------------------------------
gcc conftest.c -Wall -I. -I$(SRCPATH) -fPIE -std=gnu99 -D_GNU_SOURCE -Werror=attributes -Werror=ignored-attributes -lm -o conftest
/tmp/ccp8pwlC.s: Assembler messages:
/tmp/ccp8pwlC.s:30: Error: bad instruction `cmeq v0.8h,v0.8h,#0'
--------------------------------------------------
Failed program was:
--------------------------------------------------
int main (void) { __asm__("cmeq v0.8h, v0.8h, #0"); return 0; }
--------------------------------------------------
Finally I modified the Makefile.ffmpeg and added the --disable-asm to be able to continue.
This is my architecture:
osmc@osmc:~/tvheadend/tvheadend$ gcc -Q --help=target -march=native -mtune=native
The following options are target specific:
-mabi= aapcs-linux
-mabort-on-noreturn [disabled]
-mandroid [disabled]
-mapcs [disabled]
-mapcs-frame [disabled]
-mapcs-reentrant [disabled]
-mapcs-stack-check [disabled]
-march= armv8-a+crc+simd
-marm [disabled]
-masm-syntax-unified [enabled]
-mbe32 [enabled]
-mbe8 [disabled]
-mbig-endian [disabled]
-mbionic [disabled]
-mbranch-cost= -1
-mcallee-super-interworking [disabled]
-mcaller-super-interworking [disabled]
-mcmse [disabled]
-mcpu=
-mfdpic [disabled]
-mfix-cortex-m3-ldrd [disabled]
-mflip-thumb [disabled]
-mfloat-abi= hard
-mfp16-format= none
-mfpu= vfpv3-d16
-mgeneral-regs-only [disabled]
-mglibc [enabled]
-mhard-float -mfloat-abi=hard
-mlittle-endian [enabled]
-mlong-calls [disabled]
-mmusl [disabled]
-mneon-for-64bits [disabled]
-mpic-data-is-text-relative [enabled]
-mpic-register=
-mpoke-function-name [disabled]
-mprint-tune-info [disabled]
-mpure-code [disabled]
-mrestrict-it [disabled]
-msched-prolog [enabled]
-msingle-pic-base [disabled]
-mslow-flash-data [disabled]
-msoft-float -mfloat-abi=soft
-mstructure-size-boundary= 8
-mthumb [enabled]
-mthumb-interwork [disabled]
-mtls-dialect= gnu
-mtp= cp15
-mtpcs-frame [disabled]
-mtpcs-leaf-frame [disabled]
-mtune= cortex-a72
-muclibc [disabled]
-munaligned-access [enabled]
-mvectorize-with-neon-double [disabled]
-mvectorize-with-neon-quad [enabled]
-mword-relocations [enabled]
Known ARM ABIs (for use with the -mabi= option):
aapcs aapcs-linux apcs-gnu atpcs iwmmxt
Known __fp16 formats (for use with the -mfp16-format= option):
alternative ieee none
Known ARM FPUs (for use with the -mfpu= option):
auto crypto-neon-fp-armv8 fp-armv8 fpv4-sp-d16
fpv5-d16 fpv5-sp-d16 neon neon-fp-armv8
neon-fp16 neon-vfpv3 neon-vfpv4 vfp vfp3 vfpv2
vfpv3 vfpv3-d16 vfpv3-d16-fp16 vfpv3-fp16
vfpv3xd vfpv3xd-fp16 vfpv4 vfpv4-d16
Valid arguments to -mtp=:
auto cp15 soft
Known floating-point ABIs (for use with the -mfloat-abi= option):
hard soft softfp
TLS dialect to use:
gnu gnu2
Is there a way to optimize for this CPU?
Anyway compilation broke later:
/home/osmc/tvheadend/tvheadend/build.linux/ffmpeg/x265_4.1/source/common/aarch64/dct-prim.h:38:33: error: 'vqtbx1q_s8' was not declared in this scope; did you mean 'vtbx1_s8'?
38 | return vreinterpretq_s16_s8(vqtbx1q_s8(a_s8, a_s8, tbl));
| ^~~~~~~~~~
| vtbx1_s8
