We have been trying to use Cactus as SPMC on Tegra194 (pre 8.4) platforms and have faced the following issues.

Cactus_main.c – During cold boot, Cactus checks if the ffa-id for the instance of Cactus == SPM_VM_ID_FIRST. It issues FFA_ID_GET SMC to TF-A which returns the spmc_id in return. But on pre-8.4 platforms the value does not match SPM_VM_ID_FIRST and so the system assumes that the device is running on a post-8.4 CPU. The problem is that TF-A returns the spmc_id for this SMC, which seems incorrect. I don’t understand why Cactus needs to know its own VM_ID on pre-8.4 CPUs. Can we assume that only one SPMC can run on pre-8.4?
Cactus_ffa_tests.c – The ` ffa_partition_info_get_test` incorrectly queries the partition info for secondary and tertiary VMs on pre-8.4 CPUs.
In general the boot tests that execute within Cactus seem incorrect to me. Some tests expect the presence of a non-secure world payload, which is not available at this point in the boot. This leads to numerous crashes and asserts during boot.
Cactus incorrectly uses a hard-coded address 0x7300000 as the RX/TX memory base. It should be using a platform defined value instead. We do not support this memory address on Tegra194.
The debug UART in Cactus needs rework too. Right now, it only supports PL011 as the UART driver.
TF-A SPMD forwards some SMCs to the non-secure world without checking if a non-secure world payload exists. This causes crashes during cold boot.

Please let me know if you have commits for any or all of these issues. We have some WIP commits that we can push to gerrit for review, if required.

Thoughts?

-Varun