ARM Technical Support Knowledge Articles

Problems / corruption when accessing memory mapped peripheral registers in RVD

Applies to: RealView Development Suite (RVDS)

Answer

Peripheral memory mapped registers may have side effects like read or write sensitivity. For example, reading the Acknowledge register of an interrupt controller may signal the hardware to proceed with the next waiting interrupt.

RVD may indirectly cause problems for memory areas which are read or write sensitive. By default the debugger assumes that the entire memory map can be read without side effects. This allows the debugger to populate (read) the memory pane between debug events and verify writes by performing additional read requests from the same location.

You can disable this default behaviour for a specific area of memory by changing the memory attributes in the 'Memory Pane' tab of the 'Process Control' pane. Right-click in the 'Memory Pane' and select the 'Memory Mapping' option. You can now 'Create Map Entries' by right-clicking in the pane.

Each entry you create in the 'Memory Pane' will have a defined behaviour depending on the assigned memory type. For areas that contain read sensitive peripheral registers this should be set to Write Only.

It is possible to save your memory map attributes by creating a custom BCD file and attaching it to your target connection. Details can be found in the 'RealView Debugger Target Configuration Guide'. infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.rvds/index.html

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