Dear Segger Team,

We are using Segger J-Links together with a Cortex-M33 (custom silicon) for development and debugging of the
non-secure TrustZone side. Starting with version 7.84e we are seeing a popup message which we did not see with
version 7.84d and below. The message is:

"CPU_REG_Set(): Register 0 is already marked as valid."

In the J-Link log we observe:

02-00000000-00-00001310-003B: T9720 001:312.106 JLINK_WriteRegs(NumRegs = 1, Indexes: 88)
02-00000000-00-00001312-0014: T9720 001:313.366
02-00000000-00-00001312-0018: ***** Internal Error:
02-00000000-00-00001312-0049: T9720 001:313.450 CPU_REG_Set(): Register 0 is already marked as valid.
02-00000000-00-00005116-0014: T9720 005:118.482
02-00000000-00-00005116-000F: ***** Error:
02-00000000-00-00005116-0041: T9720 005:118.532 Reading register 20 failed: Unspecified error
02-00000000-00-00005116-002B: T9720 005:118.541 -- BASEPRI_BASE0=0x000
02-00000000-00-00005116-0028: T9720 005:118.549 - 3806.443ms returns 0
03-00000000-00-00005116-0035: ERROR: Reading register 20 failed: Unspecified error

It is not clear to us from the changelog what might have caused this issue from 7.84d to 7.84e.

I do have J-Link log files available for the same test sequence on 7.84d and 7.84e which I can share with Segger (but do not want to post to the general public; please feel free to contact me via e-mail).


Thank you for your support!
Thomas