Re: [PATCH v1 12/15] xen/riscv: introduce sbi_set_timer()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.01.2026 17:33, Oleksii Kurochko wrote:
> On 1/12/26 4:12 PM, Jan Beulich wrote:
>> On 24.12.2025 18:03, Oleksii Kurochko wrote:
>>> Introduce pointer to function which points to a specific sbi_set_timer()
>>> implementation. It is done in this way as different OpenSBI version can
>>> have different Extenion ID and/or funcion ID for TIME extension.
>>>
>>> sbi_set_time() programs the clock for next event after stime_value
>>> time. This function also clears the pending timer interrupt bit.
>>>
>>> Introduce extension ID and SBI function ID for TIME extension.
>>>
>>> Implement only sbi_set_timer_v02() as there is not to much sense
>>> to support earlier version and, at the moment, Xen supports only v02.
>> Besides this somewhat contradicting the use of a function pointer: What
>> about the legacy extension's equivalent?
> 
> I think this is not really needed, and the same implementation can be used for
> both the Legacy and TIME extensions, since the API is identical and the only
> difference is that|sbi_set_timer()| was moved into a separate extension.
> 
> Since Xen reports to the guest that it supports SBI v0.2, it is up to the 
> guest
> implementation to decide why it is still using|sbi_set_timer()| from the
> Legacy extension instead of the TIME extension.
> 
> I think that I can add Legacy extension equivalent but considering that we are
> using OpenSBI v0.2 for which Time extension is available it seems for me it is
> enough to define sbi_set_timer to sbi_set_timer_v02() for now.

Feels like here you're negating what just before you wrote in reply to 10/15.
IOW - I'm now sufficiently confused. (Just consider if you ran Xen itself as
a guest of the very same Xen. From what you said for 10/15, it would end up
not seeing the TIME extension as available, hence would need a fallback to
the Legacy one.)

Jan