Sorry for the confusing post. I get the same behavior on qemu for both riscv64 and riscv32. I posted output from riscv32. Here is the C++ code: $ cat hello.cc #include int main() { std::cout << "Hello\n"; return 0; } From: "Kenny, Joseph P" Reply-To: "musl@lists.openwall.com" Date: Friday, March 18, 2022 at 9:42 AM To: "musl@lists.openwall.com" Subject: [EXTERNAL] [musl] C++ segfault on riscv64 I’m getting segfaults with musl for C++ code on riscv64. I have tested mipsel using qemu user mode as described below and found no issues. I’m cross-compiling using the latest riscv64-linux-musl-cross.tgz (23-Nov-2021) from musl.cc on x86_64/Fedora 35. I have confirmed that I get the following behavior for both riscv64 hardware and qemu user mode. C is fine: $ cat hello.c #include int main(int argc, char **argv) { printf("Hello\n"); return 0; } $ riscv32-linux-musl-gcc -static -g -Og hello.c -o hello $ qemu-riscv32 hello Hello C++ segfaults: $ riscv32-linux-musl-g++ -static -g -Og hello.cc -o hello $ qemu-riscv32 hello Segmentation fault (core dumped) GDB confirms the segfault in __dynamic_cast on both qmeu and riscv64 hardware. I’ll paste in the assembly below. Segfault occurs on the last instruction shown [ld a5,0(a0)]. I’ve taken this as far as my skills allow. Any ideas what’s going on here or how to debug further? Thanks 000000000007d38e <__dynamic_cast>: 7d38e: c55d beqz a0,7d43c <__dynamic_cast+0xae> 7d390: 00053803 ld a6,0(a0) 7d394: 715d addi sp,sp,-80 7d396: fc26 sd s1,56(sp) 7d398: ff083703 ld a4,-16(a6) 7d39c: ff883783 ld a5,-8(a6) 7d3a0: 84b6 mv s1,a3 7d3a2: 972a add a4,a4,a0 7d3a4: 6314 ld a3,0(a4) 7d3a6: 4805 li a6,1 7d3a8: 1812 slli a6,a6,0x24 7d3aa: e802 sd zero,16(sp) 7d3ac: ec42 sd a6,24(sp) 7d3ae: e0a2 sd s0,64(sp) 7d3b0: 842a mv s0,a0 7d3b2: ff86b503 ld a0,-8(a3) 7d3b6: e486 sd ra,72(sp) 7d3b8: f84a sd s2,48(sp) 7d3ba: f44e sd s3,40(sp) 7d3bc: f052 sd s4,32(sp) 7d3be: e402 sd zero,8(sp) 7d3c0: 04f51663 bne a0,a5,7d40c <__dynamic_cast+0x7e> 7d3c4: 611c ld a5,0(a0)