Hello, Buildroot supports building ARM 32-bit systems for ARMv8 cores (even though those would more classically run an AArch64 system). Unfortunately, it seems like uClibc-ng doesn't support this situation, as it exhibits the following build failure: CC libpthread/linuxthreads/mutex.os /tmp/ccn8SFKU.s: Assembler messages: /tmp/ccn8SFKU.s:162: Error: swp{b} use is obsoleted for ARMv8 and later /tmp/ccn8SFKU.s:186: Error: swp{b} use is obsoleted for ARMv8 and later /tmp/ccn8SFKU.s:203: Error: swp{b} use is obsoleted for ARMv8 and later /tmp/ccn8SFKU.s:224: Error: swp{b} use is obsoleted for ARMv8 and later make[1]: *** [Makerules:369: libpthread/linuxthreads/mutex.os] Error 1 See http://autobuild.buildroot.net/results/1e2e5e6c752901a818630d0c0816f43874bf… for a more detailed log. This is due to libpthread/linuxthreads/sysdeps/arm/pt-machine.h which uses the swp instruction that is not allowed on ARMv8. Best regards, Thomas -- Thomas Petazzoni, co-owner and CEO, Bootlin Embedded Linux and Kernel engineering and training https://bootlin.com