Re: [XEN][PATCH 2/7] xen/domctl: introduce XEN_DOMCTL_CDF_is_32bits

["Teddy Astie" <teddy.astie@xxxxxxxxxx>]

Hello,

Le 31/07/2025 à 11:44, Grygorii Strashko a écrit :
> Hence, this patch introduces extra "XEN_DOMCTL_CDF_is_32bits" flag which is
> intended to be used by 64bit Arches for proper configuration of domain type
> when domain is created.
>
> Now it adds initial support for this flag for Arm64 arch only. The default
> Arm64 domain type is changed to 64bit:
> - the Arm Xen boot code is handling this case properly already;
> - for toolstack case the XEN_DOMCTL_set_address_size hypercall handling
> updated to forcibly configure domain type regardless of current domain type
> configuration. Hence toolstack configures vcpus and memory after
> configuring domain type it allows to start with domain default AArch64 type
> and then switch to requested domain type and ensures all required domain
> settings applied.
>
> For Arm32 this flag is ignored.
>
> Note. For Arm64, Once toolstack is updated to probe guest binary before
> creating domain the XEN_DOMCTL_set_address_size will become obsolete.
>
> [1] https://lists.xen.org/archives/html/xen-devel/2025-07/msg01647.html
> [2] https://lists.xen.org/archives/html/xen-devel/2025-07/msg01648.html
>
> Signed-off-by: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
> ---

I would prefer it be better presented as a platform-specific enum.
Something like

```
enum xen_arch_subarch {
   XEN_ARM_SUBARCH_NATIVE = 0,
   XEN_ARM_SUBARCH_ARMV7 = 1,
   XEN_ARM_SUBARCH_AARCH64 = 2,
   // ...
}
```

As there could be cases of limited backward compatibility, or multiple
diverging subarchs variants.

Teddy


Teddy Astie | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

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