When a CP14 read command accesses a DBGPRSR or DBGOSLSR register with the control/status DbgSwEnable bit set = 0, the system generates an unexpected UNDEF exception, even in privileged mode.
The user can set the DbgSwEnable bit = 1 before reading one of these registers and then set the bit = 0 when the read is complete.
| Impact: | Minor. DBGPRSR and DBGOSLSR registers are mainly used for debug across unsupported power-down sequences. |
Work-around: | The user can set the DbgSwEnable bit = 1 before reading one of these registers and then set the bit = 0 when the read is complete. |
Configurations Affected: | Systems that use one or both ARM processors. |
| Device Revision(s) Affected: | All. No plan to fix. Refer to (Xilinx Answer 47916) - Zynq-7000 SoC Silicon Revision Differences. |
Impact Details
The DBGPRSR and DBGOSLSR registers are intended to be used as part of debug process that spans from power-down to power-up. However, the power down/up functionality is not supported.
Note: The DbgSwEnable bit is in the Control/Status Word register. This register and the DBGPRSR/DBGOSLSR registers are accessible by the DAP controller.
| Answer Number | Answer Title | Version Found | Version Resolved |
|---|---|---|---|
| 47916 | Zynq-7000 SoC Devices - Silicon Revision Differences | N/A | N/A |
| AR# 47560 | |
|---|---|
| Date | 05/25/2018 |
| Status | Active |
| Type | Design Advisory |
| Devices | |