Re: [PATCH] tools/ocaml/xc: Fix xc_physinfo() bindings

[Christian Lindig <christian.lindig@xxxxxxxxx>]

> On 8 Jun 2023, at 20:33, Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx> wrote:
> 
> +type arm_physinfo_caps =
> +  {
> +    sve_vl: int;
> +  }
> +


Does the OCaml side need to know about the structure of this value or is it 
enough to pass it around as an abstract value because all logic is on the C 
side? I assume the OCaml side needs at least a way to persist the value and 
hence needs to know some representation. 

>       Store_field(arch_obj, 0,
> +                 Val_int(MASK_EXTR(info->arch_capabilities,
> +                                   XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK) * 128));
> +

What is the “* 128” achieving as part of this encoding?

— C