LS2088A/LS1046A/LS1043A: TF-A boot flow vs PPA boot flow

[rams]

Hi,

From 18.12 LSDK, NXP has introduced TF-A boot flow for the layerscape RDBs.  

We have our custom boards based on Layerscape CPUs.  We have still not migrated to TF-A boot flow.  We are still using PPA boot flow. 

Now, we have to assess potential risks and benefits to migrate to TF-A boot flow for our products as it involves some changes in flash layout and binary upgrades for the products which are already deployed.

1) What are the benefits/advantages in moving to TF-A boot flow? Will that become mandatory at some point to use this boot flow in order to use latest kernel?

2) Is that possible to still keep PPA boot flow for future LSDK releases and update RCW, MC, u-boot and Kernel?

[yipingwang]

1. Trusted Firmware (TF-A) is an implementation of secure world software for Armv8-A. TF-A provides trusted code base complying with the Arm specifications. The TF-A boot flow consists of 5 individual boot stages running at different exception levels, as explained in the following table.

TF-A boot flow

Boot ROM -> BL2 -> BL31 ->U-boot/UEFI -> Linux

PPA boot flow

Boot ROM > U-Boot/UEFI>PPA > U-Boot/UEFI > Linux

It's not mandatory to use TF-A boot flow to use the latest Linux Kernel.

2. No planning to keep PPA boot flow for future LSDK release.