Re: [PATCH v2 03/10] arm: Modify type of actlr to register_t

[Julien Grall <julien@xxxxxxx>]

Hi Michal,

On 27/04/2021 10:35, Michal Orzel wrote:
> AArch64 registers are 64bit whereas AArch32 registers
> are 32bit or 64bit. MSR/MRS are expecting 64bit values thus
> we should get rid of helpers READ/WRITE_SYSREG32
> in favour of using READ/WRITE_SYSREG.
> We should also use register_t type when reading sysregs
> which can correspond to uint64_t or uint32_t.
> Even though many AArch64 registers have upper 32bit reserved
> it does not mean that they can't be widen in the future.
This is a pretty generic message but doesn't really explain the change 
itself and point out this is a bug (possibly latent on current HW) 
because it is implementation defined. IOW a CPU implementer may already 
have decided to use the top 32-bit without our knowledge.
Cheers,

--
Julien Grall