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ARM Cortex-A15 MPCore Processor Technical Reference Manual

ARM Cortex-A15 MPCore Processor Technical Reference Manual

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Debug10.5 Debug eventsA debug event can be either:• A software debug event.• A halting debug event.A processor responds to a debug event in one of the following ways:• Ignores the debug event.• Takes a debug exception.• Enters debug state.This section describes debug events in:• Watchpoint debug events.• Asynchronous aborts.• Debug OS Lock.See the <strong>ARM</strong> ® Architecture <strong>Reference</strong> <strong>Manual</strong> <strong>ARM</strong>v7-A and <strong>ARM</strong>v7-R edition for moreinformation on debug events.10.5.1 Watchpoint debug eventsIn the <strong>Cortex</strong>-<strong>A15</strong> <strong>MPCore</strong> processor, watchpoint debug events are always synchronous.Memory hint instructions and cache clean operations do not generate watchpoint debug events.Store exclusive instructions generate a watchpoint debug event even when the check for thecontrol of exclusive monitor fails.For watchpoint debug events, the value reported in DFAR is guaranteed to be no lower than theaddress of the watchpointed location rounded down to a multiple of 16 bytes.10.5.2 Asynchronous abortsThe processor ensures that all possible outstanding asynchronous Data Aborts are recognizedbefore entry to the debug state. The debug asynchronous aborts discarded bit,DBGDSCR.ADAdiscard, is set to 1 on entry to debug state.While in debug state with DBGDSCR.ADAdiscard set, asynchronous Data Aborts generated asa result of double bit ECC errors are not discarded. This is because the processor cannotdetermine whether the abort was generated from the debugger or from external system activity.While in debug state with DBGDSCR.ADAdiscard set, the <strong>Cortex</strong>-<strong>A15</strong> <strong>MPCore</strong> processorreports AXI bus errors by asserting nAXIERRIRQ or nINTERRIRQ pin.10.5.3 Debug OS LockDebug OS Lock is set by the powerup reset, nCPUPORESET, see Resets on page 2-11. Fornormal behavior of debug events and debug register accesses, Debug OS Lock must be cleared.For more information, see the <strong>ARM</strong> ® Architecture <strong>Reference</strong> <strong>Manual</strong> <strong>ARM</strong>v7-A and <strong>ARM</strong>v7-Redition.<strong>ARM</strong> DDI 0438I Copyright © 2011-2013 <strong>ARM</strong>. All rights reserved. 10-34ID062913Non-Confidential

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