Re: [PATCH v4 20/45] target/arm: Handle cpreg registration for missing EL

[Richard Henderson]

On 5/3/22 09:34, Peter Maydell wrote:
> "set CONST on the cpreg" is what the code does, but it's not
> what the architecture wants. In particular, if the EL2 cpreg defines
> a non-zero resetvalue then the EL3-no-EL2 CPU will get a
> "reads as constant that value" rather than "reads as zero".
> CNTHCTL_EL2 and MDCR_EL2 are examples of this.

Ah, I'd missed those.  I guess I need a third bit to indicate keeping the resetvalue, for 
e.g. VPIDR_EL2, which is why the code is written the way it is.


r~