How to set the BSOD-AFL harness in the windows guest os?

I got several questions for the BSOD-AFL Harness.
1. asm("int $3" ::"a"(HYPERCALL_BUFFER), "b"(buffer), "c"(LENGTH)); What's this mean? Since we need to set the software breakpoint during executing the target function. Is it similar to "mov rax, HYPERCALL; int 3 "
2. Are there any suggested target function? 