Re: [PATCH v3 3/4] vhost-user: introduce vhost-user API

[Laurent Vivier <lvivier@redhat.com>]

On 26/08/2024 07:26, David Gibson wrote:
>> +/**
>> + * vu_set_features_exec() - Enable features of the back-end
>> + * @vdev:	Vhost-user device
>> + * @vmsg:	Vhost-user message
>> + *
>> + * Return: false as no reply is requested
>> + */
>> +static bool vu_set_features_exec(struct vu_dev *vdev,
>> +				 struct vhost_user_msg *msg)
>> +{
>> +	debug("u64: 0x%016"PRIx64, msg->payload.u64);
> A number of these debug() messages look like they'd be pretty cryptic,
> with no indication of which part of passt they're coming from.  This
> one is especially bad.

We have in the main loop calling each vu_ function a trace:

         debug("================ Vhost user message ================");
         debug("Request: %s (%d)", vu_request_to_string(msg.hdr.request),
                 msg.hdr.request);
         debug("Flags:   0x%x", msg.hdr.flags);
         debug("Size:    %u", msg.hdr.size);

That will give:

33.1458: passt: epoll event on vhost-user command socket 73 (events: 0x00000001)
33.1458: ================ Vhost user message ================
33.1458: Request: VHOST_USER_SET_FEATURES (2)
33.1458: Flags:   0x1
33.1458: Size:    8
33.1458: u64: 0x0000000140008000

I think this provides enough context to understand the trace.

Thanks,
Laurent