a world about where to find more info on syscalls arguments
display the brk in the strace

I was hoping that since we don't mediate the brk()s, that would
constitute a good resynchronization point for diff in the strace, but
actually, the returned values differ for some reason. I can't
understand why the memory layout would be different in strace and in
simterpose.
Wait for master when forking so that it does not miss the execv
use an array of longs instead of 6 values to get the tracee's registers