Network Core access to XIP

[mnmoran]

My B0n bootloader (running on the network core) is trying to access XIP space and faulting.  This is a part of an network core upgrade.

From what I can learn from the data-sheet, it is clear that:

• the network core cannot use EasyDMA to access XIP.
• the network core cannot *execute* from the XIP space

This seems to leave open the possibility that the network core *can* access the XIP space.

My best guess is that there might be some need to give the network core permission to do so using the DCNF and/or SPU. However, the means to do this is not entirely clear from what I can find in the data-sheet documentation.

Are my assumptions correct?

If so, will you kindly point me in the right direction?

I'm using/debugging this sample:

ncs_samples/smp_dfu/ble_extFlash at master · aiminhua/ncs_samples (github.com)

I'm using the nRF5340DK.

The failure/crash happens when I try to upgrade the `net_core_app_update.bin` using the "nRF Connect" DFU on my phone.

I used the Ozone debugger on the network core to find the failure.

[mnmoran]

The nRF5340 Product Specification, Figure 27: Memory layout seems to indicate that the XIP space is not accessible by the Network Core.

By modifying the MCUBoot loader.c file to copy the (potentially large) image from XIP space into RAM and using a pointer to that RAM in the PCD transaction to update the Network Core, the BLE upgrade succeeded without crashing.

This change is a very ugly hack on top of the modifications to the loader.c  file supplied by the https://github.com/aiminhua/ncs_samples/tree/master/smp_dfu/ble_extFlash example in the sdk_change directory.

[Simon]

Hello,

Sorry for the late reply. A huge part of the suppor team has been on vacation the last days, and that is the reason.

I'll look into your questions the upcoming days.

Best regards,

Simon