Intel® Arria® 10 SX Device Errata and Design Recommendations

ID 683161
Date 8/03/2022
Public
Document Table of Contents

4.1.16. 756421: Sticky Pipeline Advance Bit Cannot be Cleared from Debug APB Accesses

Description

The Sticky Pipeline Advance bit is bit[25] of the DBGDSCR register. This bit enables the debugger to detect whether the processor is idle. This bit is set to 1 every time the processor pipeline retires one instruction. A write to DBGDRCR[3] clears this bit. Because of this erratum, the Cortex* -A9 does not implement any debug APB access to DBGDRCR[3].

Impact

The external debugger cannot clear the Sticky Pipeline Advance bit in the DBGDSCR. In practice, this makes the Sticky Pipeline Advance bit concept unusable on Cortex* -A9 processors.

Workaround

There is no practical workaround for this erratum. The only possible way to reset the Sticky Pipeline Advance bit is to assert the nDBGRESET input pin on the processor, which obviously has the side effect of resetting all debug resources in the concerned processor, and any other additional CoreSight components to which nDBGRESET is connected.

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