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icc_sre_el2 register not recognised with arm-none-eabi

PJ Nee

I am trying to access the ARMV8 system register icc_sre_el2 but get an unknown or missing system register error.

See below for the list of available registers for ARMV8

https://developer.arm.com/docs/ddi0595/e/aarch64-system-registers

When using some other registers from the list the build is successful. But anything with icc_, ich_ prefixes produces a failure.

What do I need to do to fix this? 

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  • +1

    Hi PJ,

    It seems we've missed these from binutils. For now you can work around it by using the encoding of the register.

    The assembler supports a general encoding scheme `S<op0>_<op1>_<Cn>_<Cm>_<op2`

    If you look on the page you sent for instance on https://developer.arm.com/docs/ddi0595/e/aarch64-system-registers/actlr_el2

    You'll see the values for `op0` etc.

    So again in that case these two are equivalent

    mrs x4, s3_4_c1_c0_1, x4
mrs x4, ACTLR_EL2

    We'll get these sorted as soon as possible in gas.

    That said, your description is a bit confusing, icc_sre_el2 is an AArch64 register, did you mean ICC_MSRE since you're using an arm-none-eabi?  In any case the same workaround exists, just use the right encoding.

Reply
  • +1

    Hi PJ,

    It seems we've missed these from binutils. For now you can work around it by using the encoding of the register.

    The assembler supports a general encoding scheme `S<op0>_<op1>_<Cn>_<Cm>_<op2`

    If you look on the page you sent for instance on https://developer.arm.com/docs/ddi0595/e/aarch64-system-registers/actlr_el2

    You'll see the values for `op0` etc.

    So again in that case these two are equivalent

    mrs x4, s3_4_c1_c0_1, x4
mrs x4, ACTLR_EL2

    We'll get these sorted as soon as possible in gas.

    That said, your description is a bit confusing, icc_sre_el2 is an AArch64 register, did you mean ICC_MSRE since you're using an arm-none-eabi?  In any case the same workaround exists, just use the right encoding.

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