Re: [PATCH v3 08/39] xen/riscv: implement virtual APLIC MMIO emulation

[Oleksii Kurochko <oleksii.kurochko@gmail.com>]

On 10/14/26 8:16 AM, Jan Beulich wrote:
> On 13.10.2026 18:06, Oleksii Kurochko wrote:
>> On 10/5/26 4:53 PM, Baptiste Le Duc wrote:
>>>> Guests running under Xen program interrupt routing by writing to APLIC
>>>> MMIO registers. Xen must intercept these accesses to enforce interrupt
>>>> isolation between domains and to translate guest routing intent into the
>>>> underlying physical MSI topology.
>>>>
>>>> Register the vAPLIC range with the MMIO dispatch and emulate the accesses:
>>>>    - reads and writes are masked with the domain's authorised interrupt
>>>>      bitmap, so that a guest can neither observe nor affect interrupts it
>>>>      does not own;
>>>>    - target registers are shadowed per source, so that a guest reads back
>>>>      what it wrote. The h/w register instead gets the hart index and guest
>>>>      interrupt file of the pCPU the target vCPU's interrupt file lives on,
>>>>      as the APLIC uses these fields directly to compute the MSI address. As
>>>>      long as the target vCPU has no h/w guest interrupt file, only the
>>>>      shadow copy is updated;
>>>>    - only MSI delivery mode is emulated: target writes made while the
>>>>      guest's domaincfg.DM is clear are ignored.
>>>>
>>>> Delegation (APLIC_SOURCECFG_D) is not yet supported.
>>>>
>>>> Co-developed-by: Romain Caritey <Romain.Caritey@microchip.com>
>>>> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
>>> Co-developed-by: needs a matching Signed-off-by: from Romain right after
>>> it.
>>
>> I will contact Romain and ask for his Signed-off-by.
> 
> Just to mention: Co-developed-by: can mean many things. We haven't been
> insisting on matching S-o-b before. Plus if there was an S-o-b, why
> would there want/need to be Co-developed-by: as well?

I haven't checked if it is true for Xen (my fault). I know that such 
rule is in Linux 
(https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by):
   ...
   Since Co-developed-by: denotes authorship, every Co-developed-by: 
must   be immediately followed by a Signed-off-by:
   ...

I've never thought in that way about S-o-b and I think I can agree with 
that there is no point to have Co-developed-by if there is correspondent 
S-o-b, i.e. S-o-b by default includes C-o-b.

~ Oleksii