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Observer
Observer
652 Views
Registered: ‎03-18-2019

U-Boot EL3

Hi.
Is It possible to run U-Boot with exception layer EL3.
I want to use U-Boot as the bootloader for BareMetal or FreeRTOS firmware for ZynqMP platform. The problem is that U-Boot runs with EL2, switchs EL to EL1 when start BareMetal/FreeRTOS (is built with BSP for EL3).

Thanks.

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3 Replies
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Xilinx Employee
Xilinx Employee
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Registered: ‎03-02-2016

Re: U-Boot EL3

Evethough its is not the  supported bootflow, Yes you can boot u-boot at EL3 with out any issue, you just have to skip loading ATF(bl31.elf) in the bootsequence.

Regarding hand off to EL3 app, you need to comment out the routine do_go_exec() defined in board/xilinx/zynqmp/zynqmp.c of u-boot. 

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Visitor
Visitor
123 Views
Registered: ‎01-24-2020

Re: U-Boot EL3

Has anyone been able to implement this solution?

I tired to remove BL31 from the bif for generating BOOT.bin.

the_ROM_image:
{
[bootloader, destination_cpu = a53-0] embeddedsw/lib/sw_apps/zynqmp_fsbl/src/fsbl.elf
[pmufw_image] embeddedsw/lib/sw_apps/zynqmp_pmufw/src/executable.elf
[destination_device=pl] hardware_platforms/latest/top.bit
[destination_cpu=a53-0, exception_level=el-3] u-boot-xlnx/u-boot.elf
}

After flashing BOOT.bin I get the FSBL output 


================= In Stage 4 ============
Protection configuration applied
Running Cpu Handoff address: 0x8000000, Exec State: 0
Exit from FSBL

 

Do i need to put Uboot at a certain address?  I am not sure what I am doing wrong here.

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Observer
Observer
110 Views
Registered: ‎03-18-2019

Re: U-Boot EL3

Hi.

I have made my own bootloader on FreeRTOS base.

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