Hi Jamie,

I have concerns with moving FPU configuration from platform to architecture-abstraction layer.

FPU configuration is typically configured within system configuration files that are standardized in CMSIS and provided by device vendors.

Some vendors provide also tools that auto-generate the system file based on user configuration (ex: STM32CubeMX).

Therefore it would be better to leave the FPU configuration to the platform rather than moving it into architecture-abstraction.

Best regards,

Robert

From: TF-M <tf-m-bounces@lists.trustedfirmware.org> On Behalf Of Jamie Fox via TF-M
Sent: Friday 28 August 2020 19:53
To: tf-m@lists.trustedfirmware.org
Cc: nd <nd@arm.com>
Subject: [TF-M] Changes to configure FPU at the architectural level in TF-M

Hi all,

There is a change open for review that adds configuration of FPU-related registers to the architecture-abstraction layer in TF-M, and removes this same configuration from platform support files. The reasoning for this is that these registers are defined by the Arm architecture, so FPU config can be unified for all platforms with the same architecture.

For Armv8-M, this also includes configuration to ensure that information is not leaked in FPU registers to NSPE when the SPE uses the FPU, and to permit the NSPE to access the FPU.

By default, TF-M will still be built without the FPU used in the SPE.

You can review the changes at:

https://review.trustedfirmware.org/c/TF-M/trusted-firmware-m/+/5405 Arch: Add function to configure coprocessors
https://review.trustedfirmware.org/c/TF-M/trusted-firmware-m/+/5406 Platform: Remove platform-specific FPU config

It would be especially helpful if platform owners could check that they are happy with FPU config being moved out of the platform support files.

Kind regards,

Jamie