Build issue for Raspberry Pi Architecture

[MikeCardona]

Trying to build for Raspberry pi4, with ARM based board. Error in the Makefile for the CFLAG option.

ubuntu@pi4Dragon:~/hackrf-spectrum-analyzer/src/hackrf-sweep$ make                                            
# format the src # clang-format --style=file:../../../.clang-format -i hackrf_sweep.c                         
(cd lib/hackrf/ && git reset --hard v2024.02.1 && git apply < ../../src-c/0001-hackrf_sweep-to-library-conversion-v2024.02.1.patch)
HEAD is now at 18b485e3 Merge pull request #1419 from greatscottgadgets/release
Creating directories
gcc -DHACKRF_SWEEP_AS_LIBRARY -c -fPIC -fdata-sections -ffunction-sections -O2 -march=x86-64 -Ilib/hackrf/host/libhackrf/src   -Ilib/libusb-1.0.21/include/libusb-1.0     lib/hackrf/host/libhackrf/src/hackrf.c -o obj/lib/hackrf/host/libhackrf/src/hackrf.c.o
cc1: error: unknown value ‘x86-64’ for ‘-march’
cc1: note: valid arguments are: armv8-a armv8.1-a armv8.2-a armv8.3-a armv8.4-a armv8.5-a armv8.6-a armv8.7-a armv8.8-a armv8-r armv9-a armv9.1-a armv9.2-a armv9.3-a native
make: *** [Makefile:138: obj/lib/hackrf/host/libhackrf/src/hackrf.c.o] Error 1

Doing research it appears that I wanted to update the CFLAG for the proper setting, so I update the line to:

?= -march=armv8-a

Adding the ?= as "Lazy Set If Absent"... and it worked....

So, @pavsa not sure If I hack your makefile into a mess to make it for this Pi, or this is ok, with your understanding for the ARM 64 Pi 4.

Please update with your understanding.

Thank You!