[HELP] Register setting during booting the OS on ARM A53 FVP

[lzc1001]

Description

I'm porting nuttx to FVP, and have a question during the porting. (This is my first time to port OS, hhh)
I need to set the related GIC(gic v3) registers in EL3 for boot successfully. So, does the nuttx need ARM TF-A before running the OS kernel?
Thanks!

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[xiaoxiang781216]

Description

I'm porting nuttx to FVP, and have a question during the porting. (This is my first time to port OS, hhh) I need to set the related GIC(gic v3) registers in EL3 for boot successfully. So, does the nuttx need ARM TF-A before running the OS kernel? Thanks!

no, you can create a pseudo interrupt frame and downgrade to EL1 inside NuttX if CPU start from EL3 or EL2. The common arrm64 boot code already has this code block:
https://github.com/apache/nuttx/blob/master/arch/arm64/src/common/arm64_boot.c#L105-L200

[lzc1001]

Thanks for your answer! @xiaoxiang781216
If i don't add code to set registers, the terminal would not input command. I think the UART issue from the register configuration. So, is this a bug?