5.3.4. Prefetch Abort exception

If the Prefetch Abort exception occurs when the processor branches to the destination of a branch instruction, or when it commits for execution the instruction immediately after any other waypoint, the PTM:

  1. Traces the waypoint normally, by generating one of:

    • An atom, that it outputs in an atom packet. This packet might include any atoms assembled before the exception occurred.

    • A branch address packet.

  2. Generates an exception branch address packet that identifies the Prefetch Abort exception and gives the address of the exception vector.

If the Prefetch Abort exception occurs on an instruction that follows an executed nonwaypoint instruction, the PTM:

  1. Upgrades the last instruction executed to a waypoint instruction, and generates a waypoint update packet that indicates the address of that instruction.

  2. Generates an exception branch address packet that identifies the Prefetch Abort exception and gives the address of the exception vector.

    The address that aborts is the address of the instruction that immediately follows the upgraded waypoint instruction.

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