I wrote: > gdb(1) also gets SIGILL so I have not investigated > which instruction actually causes the SIGILL. Resolved by myself: SWP and SWPB instructions have been deperecated on ARMv6 and removed since ARMv7 (because atomic LDREX and STREX insns are added). https://www.wdic.org/w/SCI/ARMv6#LDREXxE3x81xA8STREX https://translate.google.co.jp/translate?hl=ja&tab=wT&sl=ja&tl=en&u=https%3A%2F%2Fwww.wdic.org%2Fw%2FSCI%2FARMv6%23LDREXxE3x81xA8STREX The same binaries on the same SD card work fine on RPI Zero WH (which is ARMv6). Thanks, P.S. Linux/arm has SWP/SWPB emulation for ARMv7 and later? http://lists.infradead.org/pipermail/linux-arm-kernel/2009-December/006331.html --- Izumi Tsutsui