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 Zynq-7000 Device Advisory Master Answer Record |
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.