1cc8c45c54
support its -k argument: kern.proc.kstack - dump the kernel stack of a process, if debugging is permitted. This sysctl is present if either "options DDB" or "options STACK" is compiled into the kernel. Having support for tracing the kernel stacks of processes from user space makes it much easier to debug (or understand) specific wmesg's while avoiding the need to enter DDB in order to determine the path by which a process came to be blocked on a particular wait channel or lock.