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Boot strapping an LS1043A

Question asked by Yaron Alterman on Feb 19, 2018
Latest reply on Feb 21, 2018 by Yaron Alterman

Hello, I am trying to write some basic bootstrap code for an LS1043A processor.

At reset the processor comes up at EL3/secured of course, and I would like to bring it to a none-secure EL1 and branch to my application from there.

 

At first I need (to my understanding) to transition to EL2/non-secure on the way to EL1.

Configuring the SCR_EL3 register goes well, and so I get to EL3/non-secure mode. 

I then configure the SPSR_EL3 with 0x3c9 (9 being the encoding for EL2 using it's stack pointer), and ELR_EL3 with my EL2_entry address. Then I call eret.

 

What happens next is I get a sync external instruction abort.

 

Any idea why this is happening? any help would be appreciated.

 

Thank,

Yaron

 

Code snippet:

mov x0, #0x501 //aarch64 + non - secure state

msr scr_el3, x0 //move to non-secure state

 

mov x0, #0x3c9 //prepare transition to EL2

msr spsr_el3, x0

 

adr x0, el2_entry

msr elr_el3, x0

 

eret

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