Re: [PATCH v2 3/3] tun: Set num_buffers for virtio 1.0

Akihiko Odaki
2025-01-10T11:12:32Z

On 2025/01/10 19:23, Michael S. Tsirkin wrote:
> On Fri, Jan 10, 2025 at 11:27:13AM +0800, Jason Wang wrote:
>> On Thu, Jan 9, 2025 at 2:59 PM Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
>>>
>>> The specification says the device MUST set num_buffers to 1 if
>>> VIRTIO_NET_F_MRG_RXBUF has not been negotiated.
>>
>> Have we agreed on how to fix the spec or not?
>>
>> As I replied in the spec patch, if we just remove this "MUST", it
>> looks like we are all fine?
>>
>> Thanks
>
> We should replace MUST with SHOULD but it is not all fine,
> ignoring SHOULD is a quality of implementation issue.
>

Should we really replace it? It would mean that a driver conformant with
the current specification may not be compatible with a device conformant
with the future specification.

We are going to fix all implementations known to buggy (QEMU and Linux)
anyway so I think it's just fine to leave that part of specification as is.