Re: [PATCH v5 1/3] xen/mm: Introduce mm-types.h

[Jan Beulich <jbeulich@xxxxxxxx>]

On 25.04.2025 15:48, Andrew Cooper wrote:
> On 25/04/2025 2:13 pm, Jan Beulich wrote:
>> On 25.04.2025 15:05, Andrew Cooper wrote:
>>> On 25/04/2025 1:48 pm, Jan Beulich wrote:
>>>> On 25.04.2025 13:24, Andrew Cooper wrote:
>>>>> The type used for pagetable attributes/permissions is currently unsigned 
>>>>> int,
>>>>> but needs to become architecture dependent as PPC needs unsigned long.
>>>>>
>>>>> Introduce mm-types.h to house pte_attr_t.
>>>>>
>>>>> Given the new toolchain baseline, we can use __has_include() now to 
>>>>> remove the
>>>>> need for boilerplate on most architectures.
>>>> That's true now, when it's just pte_attr_t that's there. Memory management,
>>>> however, is pretty different between architectures, so I wonder if in the
>>>> longer run any one will remain that actually can use the common header.
>>> Anything in xen/mm.h is common and needs architectures to provide (or
>>> use the defaults) the bits required.
>>>
>>> asm/mm{,-types.h} still exist (when necessary) to provide the
>>> arch-specific extensions.
>> Sure, but you kind of avoid my question: Are you reasonably certain more than
>> one arch will still be able to use the defaults, once a few more things 
>> appear
>> in this header? (IOW: Won't we be better off having each arch have its
>> asm/mm-types.h right away?)
> 
> I can't predict the future, but my gut feeling is that it's not going to
> diverge very much.
> 
> If needs be, we can go to conditional override for specific bits.  Or,
> if I'm wrong, I'm wrong.  It's not hard to change.

Well, feel free then to put in with Oleksii's R-b.

Jan