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how does ARMv8 switch to run application(EL0) from kernel(EL1)?

yan.wy

hi experts,

I am studying the ARMv8 exception levels. I have a question about ELs.

EL1 is described to run OS kernel and EL0 is application level.   

The exception levels change only occur on exception or exception return.

In ARMv7, the instruction "msr CPSR_c, #usr_mode" can change into USR mode.

In ARMv8, EL0 can run "SVC" instruction to generate exception and switch to EL1, but how to switch to EL0 from EL1 when kernel bootup?

When a v8 board power on, run bootloader and kernel which is on EL1, after kernel bootup, how does switch into EL0 to run application?

     

Thanks for your attention!

Best Regards,

Yan

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