On 22.04.21 17:16, Jan Beulich wrote:
> On 22.04.2021 17:10, Juergen Gross wrote:
>> Some features of Xen can be assumed to be always present, so add a
>> central check to verify this being true and remove the other checks.
>>
>> Juergen Gross (3):
>>    xen: check required Xen features
>>    xen: assume XENFEAT_mmu_pt_update_preserve_ad being set for pv guests
>>    xen: assume XENFEAT_gnttab_map_avail_bits being set for pv guests
> 
> I wonder whether it's a good idea to infer feature presence from
> version numbers. If (at some point in the past) you had inferred
> gnttab v2 being available by version, this would have been broken
> by its availability becoming controllable by a command line option
> in Xen.

I'm testing the feature to be really present when booting and issue a
message if it is not there.

Juergen