Bug 46

Version 3

    We've confirmed that we have a bug in the MPB bypass logic.

     

    The bug is hit for bypass operations that get stalled due to core0/core1 arbitration.

     

    During a bypass operation, a packet is forwarded directly to the MPB. However, a secondary signal is generated to prevent the packet from being put on the mesh.

     

    When both cores issue requests near the same time, the MIU arbitration will stall one core while it services the other core.

     

    Stalls on bypass requests cause the "mesh prevention signal" to not be asserted. This causes an unintended packet to be put on the mesh which ultimately can cause data corruption in the MPB.  With this in mind, we recommend that the bypass feature not be used.

     

    Severity ... Major ... Function works but has sever side effects.

    P3 ... no fix planned.