Stalling

In the initial implementation, if a start key is specified and the designated domain is busy, the process stalls. If the process is still at this point when the busy domain becomes available the jump will proceed quickly.
Although there is still a process in a stalled domain it consumes few resources.

Concomitantly, if the situation leading to the stall changes in some way other than the jumpee becoming available, the jumper will not proceed until the next checkpoint restart or the jumpee becoming available. Thus if the SVC instruction that had caused the explicit jump were changed to a NOP, the domain would remain stalled despite its process and lack of an obstacle.

Normally programs stalled on a domain are restarted in the order that they became stalled. This is not always done. A proposed modification to the kernel would cause jumps to busy domains via start keys with databytes greater than 239 to be placed at the head of the stall queue.

If the jumpee's parameter string spans a page boundary, part of the parameters may be copied before the jump completes.

A process will enter the jumpee. If the meter is dry the jumpee will try to jump. {The process disappears from the new domain unless there is a valid meter. See (p3,powrdn).}

Trapping Due to Rejected Order Codes

When the order code is not zero and the gate is not a restart key and bit 4 {(recec)} in the entry block is 0 the following extra action occurs:
After the key parameters and other data parameters have been passed to the jumpee and before the domain enters the running state, the first byte of the jumpee's trap code is set to 2, and the jumper's order code is placed in the right 4 bytes of the jumpee's trap code.

{tentative}If the gate is a fault key then the current value in the jumpee's trap code is presumably that produced by the action described at (fault-act-one). One of the following two actions occur:

If the jumper's order code is zero then the jumpee's trap code is set to 0.

If the jumper's order code is not zero, then order code's right seven bits are placed in the right bits of byte one of the jumpee's trap code. This completes the report intended for the domain keeper describing the nature of some unsuitable memory reference by the domain. See (p1,fault-act).

The {jumpee's} instruction execution is ended {completed, nullified, etc.} as it would have been if the order code had been zero. {E.g., if the gate is a fault key to a domain that suffered a memory trap to a segment keeper, the jumpee's instruction is nullified.}

See also (p1,desjtrap).