When building a project that works with the SDK 1.5.0, I get the following...
r@mint:~/ncs.1.6.0-rc2/nrf/nordic_assist/nordic$ west build -b nrf9160dk_nrf9160ns
[0/12] Performing build step for 'spm_subimage'
ninja: no work to do.
[2/10] Linking C executable zephyr/zephyr_prebuilt.elf
FAILED: zephyr/zephyr_prebuilt.elf zephyr/zephyr_prebuilt.map
: && ccache /home/r/gnuarmemb/bin/arm-none-eabi-gcc zephyr/CMakeFiles/zephyr_prebuilt.dir/misc/empty_file.c.obj -o zephyr/zephyr_prebuilt.elf -Wl,-T zephyr/linker_zephyr_prebuilt.cmd -Wl,-Map=/home/r/n cs.1.6.0-rc2/nrf/nordic_assist/nordic/build/zephyr/zephyr_prebuilt.map -Wl,--whole-archive app/libapp.a zephyr/libzephyr.a zephyr/arch/common/libarch__common.a zephyr/arch/arch/arm/core/aarch32/libarch__ arm__core__aarch32.a zephyr/arch/arch/arm/core/aarch32/cortex_m/libarch__arm__core__aarch32__cortex_m.a zephyr/arch/arch/arm/core/aarch32/cortex_m/cmse/libarch__arm__core__aarch32__cortex_m__cmse.a zephyr/ arch/arch/arm/core/aarch32/mpu/libarch__arm__core__aarch32__mpu.a zephyr/lib/libc/newlib/liblib__libc__newlib.a zephyr/lib/posix/liblib__posix.a zephyr/soc/arm/common/cortex_m/libsoc__arm__common__cortex_m .a zephyr/boards/arm/nrf9160dk_nrf9160/libboards__arm__nrf9160dk_nrf9160.a zephyr/subsys/net/libsubsys__net.a zephyr/subsys/net/ip/libsubsys__net__ip.a zephyr/subsys/random/libsubsys__random.a zephyr/dri vers/gpio/libdrivers__gpio.a zephyr/drivers/serial/libdrivers__serial.a zephyr/drivers/entropy/libdrivers__entropy.a modules/nrf/lib/nrf_modem_lib/lib..__nrf__lib__nrf_modem_lib.a modules/nrf/lib/at_cmd/l ib..__nrf__lib__at_cmd.a modules/nrf/lib/at_notif/lib..__nrf__lib__at_notif.a modules/nrf/lib/at_cmd_parser/lib..__nrf__lib__at_cmd_parser.a modules/nrf/lib/lte_link_control/lib..__nrf__lib__lte_link_contr ol.a modules/nrf/lib/modem_info/lib..__nrf__lib__modem_info.a modules/nrf/lib/fatal_error/lib..__nrf__lib__fatal_error.a modules/nrf/lib/modem_key_mgmt/lib..__nrf__lib__modem_key_mgmt.a modules/nrf/lib/da te_time/lib..__nrf__lib__date_time.a modules/nrf/subsys/fw_info/lib..__nrf__subsys__fw_info.a modules/hal_nordic/nrfx/libmodules__hal_nordic__nrfx.a /home/r/ncs.1.6.0-rc2/nrfxlib/nrf_modem/lib/cortex-m33/s oft-float/libmodem.a -Wl,--no-whole-archive zephyr/kernel/libkernel.a zephyr/CMakeFiles/offsets.dir/arch/arm/core/offsets/offsets.c.obj -L"/opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-ea bi/9.2.1/thumb/v8-m.main/nofp" -L/home/r/ncs.1.6.0-rc2/nrf/nordic_assist/nordic/build/zephyr -lgcc ../../otdoa/CortexM33/libotdoa.a ../../fft/CortexM33/libfft.a ../../loc_server/CortexM33/libloc_server.a zephyr/arch/common/libisr_tables.a -mcpu=cortex-m33 -mthumb -mabi=aapcs -Wl,--gc-sections -Wl,--build-id=none -Wl,--sort-common=descending -Wl,--sort-section=alignment -Wl,-u,_OffsetAbsSyms -Wl,-u, _ConfigAbsSyms -nostdlib -static -no-pie -Wl,-X -Wl,-N -Wl,--orphan-handling=warn spm/libspmsecureentries.a -lm -Wl,-lc -L"/home/r/gnuarmemb/arm-none-eabi"/lib/thumb/v8-m.main/nofp -u_printf_float -u_scanf_float -Wl,-lgcc -lc -specs=nano.specs && cd /home/r/ncs.1.6.0-rc2/nrf/nordic_assist/nordic/build/zephyr && /usr/bin/cmake -E echo
/opt/gcc-arm-none-eabi-9-2019-q4-major/bin/../lib/gcc/arm-none-eabi/9.2.1/../../../../arm-none-eabi/bin/ld: error: ../../otdoa/CortexM33/libotdoa.a(otdoa_nordic_at.o) uses VFP register arguments, zephyr/zephy r_prebuilt.elf does not