Re: [PATCH v4 1/3] domctl: introduce a new domain create flag, XEN_DOMCTL_CDF_disable_fifo, ...

[Jan Beulich <jbeulich@suse.com>]

On 25.11.2020 10:20, Jan Beulich wrote:
> On 24.11.2020 20:17, Paul Durrant wrote:
>> --- a/xen/include/public/domctl.h
>> +++ b/xen/include/public/domctl.h
>> @@ -70,9 +70,11 @@ struct xen_domctl_createdomain {
>>  #define XEN_DOMCTL_CDF_iommu          (1U<<_XEN_DOMCTL_CDF_iommu)
>>  #define _XEN_DOMCTL_CDF_nested_virt   6
>>  #define XEN_DOMCTL_CDF_nested_virt    (1U << _XEN_DOMCTL_CDF_nested_virt)
>> +#define _XEN_DOMCTL_CDF_disable_fifo  7
>> +#define XEN_DOMCTL_CDF_disable_fifo   (1U << _XEN_DOMCTL_CDF_disable_fifo)
> 
> Despite getting longish, I think this needs "evtchn" somewhere in
> the name. To keep size bounded, maybe XEN_DOMCTL_CDF_no_fifo_evtchn?
> 
>>  /* Max XEN_DOMCTL_CDF_* constant.  Used for ABI checking. */
>> -#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_nested_virt
>> +#define XEN_DOMCTL_CDF_MAX XEN_DOMCTL_CDF_disable_fifo
> 
> While not directly related to this patch, I'm puzzled by the
> presence of this constant: I've not been able to find any use of
> it. In particular you did have a need to modify
> sanitise_domain_config().

So it was you to introduce this, right away without any user, in
7fb0e134f8c6 ("tools/ocaml: abi: Use formal conversion and check
in more places"). The only reference is from what I regard as a
comment (I don't speak any ocaml, so I may be wrong). Could you
clarify why we need to maintain this constant?

Thanks, Jan