Hi, What does the PTRACE_SETSIGINFO ptrace command do? I can see in kernel/ptrace.c:ptrace_request() it calls ptrace_setsiginfo(), passing it the child's (tracee's) task descriptor and siginfo_t instance originally passed in from user space. ptrace_setsiginfo() sets child's last_siginfo to the siginfo_t instance passed in. Now there are only two places where a child->last_siginfo's value is read are in kernel/ptrace.c: 1. by the ptrace command PTRACE_GETSIGINFO 2. by the ptrace command PTRACE_LISTEN There doesn't seem to be a place where value of last_siginfo is read by signal handling code. There is however this comment in kernel/signal.c:ptrace_signal(): /* * Update the siginfo structure if the signal has * changed. If the debugger wanted something * specific in the siginfo structure then it should * have updated *info via PTRACE_SETSIGINFO. */ Where does PTRACE_SETSIGINFO update *info? Thanks, Okash