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ARMv8 Exception level on Startup

Ajeesh

Hi,

When i power on a ARM cortex A57, How many of the 4 Exception levels will be supported?

How can i set such that only exception levels EL0 and EL1 are supported in my program? How can i activate each exception levels?

I have to set it such that normally the app should work on EL0 and when an exception occurs, it should go to EL1. How can i do that?

 

regards,

Ajeesh

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  • 0 in reply to Martin Weidmann
    Hi,
    Thanks for the reply.
    So if the board start up in EL3, when the IRQ ocuurs, Is it safe to assume that executed handler will be the handler from the vector table for EL3 only?
    How do i take an exception to the higher level(EL0 - EL1 etc..)?
    i meant, How do i chose a particular interrupt should occur in a particular exception level?

    >> Can I ask why you want to take this approach?
    -- I have some code (including startup) written for arm cortex-A9(a bare-minimum OS with a simple scheduler). I would like to port the code without any change to Aarch64. Only IRQ was enabled in the previous case. No FIQ, no SWI, no MMU, just a start up and a scheduler that schedule the tasks i create on priority base.
    I am not quite getting this 4 exception states. Wouldn't it be easier to do the above in a single exception state?

    regards,
    Ajeesh
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  • 0 in reply to Martin Weidmann
    Hi,
    Thanks for the reply.
    So if the board start up in EL3, when the IRQ ocuurs, Is it safe to assume that executed handler will be the handler from the vector table for EL3 only?
    How do i take an exception to the higher level(EL0 - EL1 etc..)?
    i meant, How do i chose a particular interrupt should occur in a particular exception level?

    >> Can I ask why you want to take this approach?
    -- I have some code (including startup) written for arm cortex-A9(a bare-minimum OS with a simple scheduler). I would like to port the code without any change to Aarch64. Only IRQ was enabled in the previous case. No FIQ, no SWI, no MMU, just a start up and a scheduler that schedule the tasks i create on priority base.
    I am not quite getting this 4 exception states. Wouldn't it be easier to do the above in a single exception state?

    regards,
    Ajeesh
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