Re: [PATCH 4/4] xen/version: Introduce non-truncating XENVER_* subops

[Julien Grall <julien@xxxxxxx>]

Hi Andrew,

On 03/01/2023 20:09, Andrew Cooper wrote:
> diff --git a/xen/include/public/version.h b/xen/include/public/version.h
> index c8325219f648..cf2d2ef38b54 100644
> --- a/xen/include/public/version.h
> +++ b/xen/include/public/version.h
> @@ -19,12 +19,20 @@
>   /* arg == NULL; returns major:minor (16:16). */
>   #define XENVER_version      0
>   
> -/* arg == xen_extraversion_t. */
> +/*
> + * arg == xen_extraversion_t.
> + *
> + * This API/ABI is broken.  Use XENVER_extraversion2 instead.
I read this as newer tools should never try to call XENVER_extraversion. 
But I don't think this is what you intend to say, correct? If so, I 
would say that an OS should first try XENVER_extraversion2 and then 
fallback to XENVER_extraversion if it returns -ENOSYS.
Same goes for the new hypercalls.

Cheers,

--
Julien Grall