Hi Suresh,
> I am of the belief that MCUboot will be a very thin shim layer over the FWU API to provide the compatibility interface to legacy software and most of the work that was done earlier in MCUboot is pushed down into the
FWU partition.
Are you suggesting that the software stack might look like this:
Update client application
|
| Function call
V
MCUBoot user API
Shim layer
|
| Function call
V
FWU API
|
| TF-M psa_call() etc.
V
FWU Partition
|
| Function call
V
MCUBoot user API
MCUBoot engine
This looks like it has one more layer than it needs, as either:
Are you only considering this software stack for a system where touching the update client application source code is not possible (needed for option #1 above)? – and you also cannot introduce a custom MCUBoot RoT Service partition (option
#2 above) so you want to reuse TF-M’s existing FWU API and partition?
Regards,
Andrew
From: TF-M <tf-m-bounces@lists.trustedfirmware.org>
On Behalf Of Suresh Marisetty via TF-M
Sent: 25 May 2021 02:37
To: Sherry Zhang <Sherry.Zhang2@arm.com>; tf-m@lists.trustedfirmware.org
Cc: nd <nd@arm.com>
Subject: Re: [TF-M] Firmware update API - MCUboot update
Hi Sherry,
Thanks for the info. Wondering if there is some documentation or powerpoint explaining how the MCUBoot is changed to accommodate the FWU API.
Details that would help:
I am of the belief that MCUboot will be a very thin shim layer over the FWU API to provide the compatibility interface to legacy software and most of the work that was done earlier in MCUboot is pushed down into the FWU
partition.
The other way to look at it is: If somebody wants to replace MCUboot with a simple BL to integrate it tightly into TFM, what would that look like?
thanks
Suresh Marisetty
Infineon Semiconductor Corporation
From: Sherry Zhang <Sherry.Zhang2@arm.com>
Sent: Thursday, May 13, 2021 7:51 PM
To: Marisetty Suresh (CYSC CSS ICW SW SSE) <Suresh.Marisetty@infineon.com>;
tf-m@lists.trustedfirmware.org
Cc: nd <nd@arm.com>
Subject: RE: Firmware update API - MCUboot update
|
Caution: This e-mail originated outside Infineon Technologies. Do not click on links or open attachments
unless you validate it is safe. |
Hi Suresh,
The MCUboot update functionality is about validating the existing images on the device which is different from that of the firmware update service which follows mostly with the
PSA Firmware Update API spec.
We designed a shim layer between the firmware update partition and bootloader. A specific bootloader can be ported into the firmware update partition via that shim layer. Please refer to the
firmware update service document. In the MCUboot based shim layer implementation, it calls some user/public APIs provided by MCUboot to achieve its functionality. For example, the Firmware Update API spec describes that psa_fwu_install() API should validate
the image or defer the validation to a system reboot. In the MCUboot shim layer implementation, it calls the boot_write_magic() API to mark the image as a candidate image for MCUboot and defers the image validation to a system reboot. Please refer to
this link.
Can you please provide more specific suggestion or questions?
Regards,
Sherry Zhang
From:
Suresh.Marisetty@infineon.com <Suresh.Marisetty@infineon.com>
Sent: Thursday, May 13, 2021 11:40 PM
To: Sherry Zhang <Sherry.Zhang2@arm.com>;
tf-m@lists.trustedfirmware.org
Cc: nd <nd@arm.com>
Subject: RE: Firmware update API - MCUboot update
Hi Sherry,
Please take a closer look at the MCUboot and TFM might want to have a clear position/distinction between these two and how to transition from MCUboot update to this mechanism or it could be that they complement each other.
thanks
Suresh Marisetty
Infineon Semiconductor Corporation
From: Sherry Zhang <Sherry.Zhang2@arm.com>
Sent: Wednesday, May 12, 2021 8:55 PM
To: Marisetty Suresh (CYSC CSS ICW SW SSE) <Suresh.Marisetty@infineon.com>;
tf-m@lists.trustedfirmware.org
Cc: nd <nd@arm.com>
Subject: RE: Firmware update API - MCUboot update
|
Caution: This e-mail originated outside Infineon Technologies. Do not click on links or open attachments
unless you validate it is safe. |
Hi Suresh,
The firmware update service APIs are for updating the firmware. The functionalities of these APIs includes loading the image into its target device(flash), verifying the image and installing it and so on.
The user can call the these APIs to achieve update images. For example, in the
integration of TF-M and the FreeRTOS OTA, the OTA agent calls the firmware update service APIs to achieve an image update remotely.
I guess that the “MCUboot update services” you mentioned refers to the functionality of MCUboot which acts as a bootloader. As a bootloader, it can verify the image which already exists on the device and chose the right
image to start up. But it cannot, for example, load the image into device or control the image update process.
The firmware update partition calls some user APIs provided by MCUboot to cooperate with it. You can refer to
https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/docs/technical_references/tfm_fwu_service.rst#n75.
Regards,
Sherry Zhang
From: TF-M <tf-m-bounces@lists.trustedfirmware.org>
On Behalf Of Suresh Marisetty via TF-M
Sent: Thursday, May 13, 2021 11:09 AM
To: tf-m@lists.trustedfirmware.org
Subject: [TF-M] Firmware update API - MCUboot update
Hi,
I would like to see if there is any guidance/documentation on how to coordinate between the firmware update services API with that of MCUboot.
Does the use of this API make the MCUboot update services redundant?
thanks
Suresh Marisetty
Infineon Semiconductor Corporation
Lead Member of Technical Staff
CYSC CSS ICW SW SSE
Mobile: +5103863997
Suresh.Marisetty@infineon.com