sched_4bsd startup crash trying to run a bound thread on an AP that hasn't started

[Ryan Stone]

On Mon, Apr 25, 2011 at 2:58 PM, John Baldwin <jhb at freebsd.org> wrote:
>
> Yes, I would perhaps tweak the comment to reflect the full if statement
> though.  Maybe something like:
>
> /*
>  * If SMP is started and the thread is pinned or otherwise limited to
>  * a specific set of CPUs, queue the thread to a per-CPU run queue.
>  * Otherwise, queue the thread to the global run queue.
>  */

That looks fine, but I'm going to add a sentence explaining why the
smp_started condition is necessary:

/*
 * If SMP is started and the thread is pinned or otherwise limited to
 * a specific set of CPUs, queue the thread to a per-CPU run queue.
 * Otherwise, queue the thread to the global run queue.
 *
 * If SMP has not yet been started we must use the global run queue
 * as per-CPU state may not be initialized yet and we may crash if we
 * try to access the per-CPU run queues.
 */