Hi Florian,

I can give some general answers to your questions and hopefully get to answering your real questions with further discussion. Please feel free to ask more questions if this does not help.

...

I noticed that TF-A is designed to load FIP Image but the U-Boot

Environment have a different format. How to access the QSPI NOR memory? NXP specific driver?

[RK] TF-A generally provides frameworks to do most things and does not provide device specific drivers but for SPI NOR, there are drivers under drivers/mtd/nor that could potentially be used. You will likely need to implement the appropriate platform hooks for the SPI bus itself to use it. The TF-A IO framework has the io_mtd layer that can be hooked into a nor device. drivers/st/spi/stm32_qspi.c seems to use all of this and should be a good example(perhaps some one from ST can chime in too). if you hook you SPI driver to the TF-A layers correctly, there should be nothing preventing you from accessing the uboot environment partition. Also, TF-A's primary/default format for firmware images is FIP but definitely does not preclude a platform from using it's own format.

...

The bl2 is designed to load only one FIP image, is it possible to add

an additional entry ? [RK] Not really. BL2 is fairly generic and you should be able to hook any image format to it. If you must use the FIP format, you can map your images to existing image id's to create a FIP with any image that you have. Once again, FIP is fairly flexible and generally treats firmware images in the package as blob's.

...

if we want to use a secure boot in the future

[RK] Like with the above things, the Trusted Board Boot framework is flexible and you should be able to implement secure boot on FIP and other formats. TF-A provides an implementation of the TBBR specification for secure boot.

It should be possible to implement the algorithm below, if you have an appropriate platform port, from what i gather in your question below.

Thanks -Raghu

On 5/13/20 5:40 AM, florian.manoel--- via TF-A wrote:

Hello TF-A mail list,

I’m new here, so I quickly introduce myself. I am Florian Manoel, working as firmware developer at Siemens in Karlsruhe, Germany. Recently, we decided to start some development based on ARM processor, the theme TF-A is new for us.

Currently, we have a custom board equipped with the processor NXP Layerscape LS1043a. So far, everything is working as planned, the PreBootLoader (TF-A) boots the bootloader (U-Boot) that’s boots linux on top. However, we want to have the possibility to boot an alternative u-boot FIP image, I explain: We use as boot source a QSPI NOR memory. In this memory are stored ‘bl2_qspi.pbl’, 2 times ‘fip.bin’, the u-boot environment and some micro-code. We want to select the u-boot image to be booted according to the value of a specific variable stored in the u-boot environment ‘u-boot-select’. The algo is, for my eye, relatively simple :

Start

• Check value of the u-boot variable ‘u-boot-select’

• Check if the corresponding u-boot image is valid, if not select the

alternative one

• Boot selected u-boot image

End

We want this functionality in case an u-boot image is broken (ex: power OFF during U-Boot update).

I already went through the source code and it rose more question than it answered. For example: I noticed that TF-A is designed to load FIP Image but the U-Boot Environment have a different format. How to access the QSPI NOR memory? NXP specific driver? The bl2 is designed to load only one FIP image, is it possible to add an additional entry ? On top of it come the question of the reliability and what will happen if we want to use a secure boot in the future..

I am looking for advice and support on this specific topic. Thanks for your support,

Mit freundlichen Grüßen Florian Manoël

Siemens AG Digital Industries Process Automation Software House Khe DI PA CI R&D 2 Östliche Rheinbrückenstr. 50 76187 Karlsruhe, Deutschland Tel.: +49 721 595-1433 mailto:florian.manoel@siemens.com www.siemens.com/ingenuityforlife https://siemens.com/ingenuityforlife

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