The BF70x datasheet proclaims "Fast secure boot for IP protection", but it seems to be anything but fast in practice.
In my testing, a mere 6,948 byte BFp loader image with the BF70x (silicon revision 1.1) takes a glacial 183.8 milliseconds between when the SPI transfer finishes and execution is transferred to the user code.
In a non-secure mode, this time is practically instantaneous.
What am I missing? Why is a high performance DSP with integrated SHA accelerator so darn slow (37801 bytes/sec)?
P.S.: if Analog Devices ever makes a revision to EE-366, they really owe it to the would-be reader to mention the 0x80000002 "BCODE" attribute (presently only documented in the ADSP-BF70x Blackfin+ Processor Hardware Reference in the Secure Boot section). It is presently omitted from the EE-366 attribute list. When signtool.exe inhales a loader image, it discards the -bcode argument provided to elfloader.exe, and the resultant image is painfully slow to boot (since it defaults the slowest SPI single-bit mode). Note that this slow-as-molasses time is in addition to the secure boot image verification described further above.