External Bus Interface
13-40 MPC823e REFERENCE MANUAL MOTOROLA
EXTERNAL BUS
13
INTERFACE
The local bus interface block implements a reservation “flag” for the local bus master. The
reservation “flag” is set by the local bus interface when a load with reservation is issued by
the local bus master and the reservation address is located on the remote bus. The “flag” is
reset when an alternative master on the remote bus accesses the same location in a write
cycle. If the MPC823e begins a memory cycle to the previously reserved address (located
in the remote bus) as a result of a stwcx instruction, one of the following conditions can
occur:
• If the reservation “flag” is set, the local bus interface acknowledges the cycle in a normal
way.
• If the reservation “flag” is reset, the local bus interface must assert KR
. However, the
local bus interface must either not perform the remote bus write access or abort it if the
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