I have a BF70x application which cannot boot in secure mode. The same application boots without issue using non-secure mode
ADSP-BF70x processors support Secure Booting, where the loader stream is digitally signed and/or encrypted using the new signtool utility, and the processor's Boot Kernel decrypts the stream and authenticates the signature before permitting the stream to boot. Silicon anomaly 19000022 describes a problem processing "fill blocks" when booting in secure mode, which causes the boot to fail.
To avoid this problem, build the loader stream using the elfloader's -NoFillBlock switch, which can be added under ‘Project: Preferences: C/C++ Build: Settings: CrossCore Blackfin Loader: Additional Options’.
There is no problem processing "fill blocks" in non-secure mode. You can build the loader stream using the elfloader’s default of creating “fill blocks” for non-secure booting.