- * Maximum number of asynchronous contexts the kernel creates.
- *
- * -1UL has a special meaning: the kernel manages the optimal
- * size of the async pool.
- *
- * Note: this field should be valid for the lifetime of async
- * processing, because future kernels detect changes to this
- * field. (enabling user-space to control the size of the async
- * pool in a low-overhead fashion)
+ * The head task can become a cachemiss thread later on
+ * too, if it blocks - so it needs its separate thread
+ * stack and start address too:
+ */
+ unsigned long head_stack;
+ unsigned long head_eip;
+
+ /*
+ * Newly started async kernel threads will take their
+ * user stack and user start address from here. User-space
+ * code has to check for new_thread_stack going to NULL
+ * and has to refill it with a new stack if that happens.