Re: [PATCH kvmtool 3/5] virtio/net: Warn if virtio_net is implicitly enabled

[Andre Przywara <andre.przywara@arm.com>]

On Tue, 18 Jan 2022 00:12:01 +0200
Martin Radev <martin.b.radev@gmail.com> wrote:

Hi,

> The virtio_net device is implicitly enabled if user doesn't
> explicitly specify that virtio_net is disabled. This is
> counter-intuitive to how the rest of the virtio commandline
> works.
> 
> For backwards-compatibility, the commandline parameters are
> not changed. Instead, this patch prints out a warning if
> virtio_net is implicitly enabled.
> 
> Signed-off-by: Martin Radev <martin.b.radev@gmail.com>
> ---
>  virtio/net.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/virtio/net.c b/virtio/net.c
> index 9a25bfa..ab75d40 100644
> --- a/virtio/net.c
> +++ b/virtio/net.c
> @@ -1002,6 +1002,9 @@ int virtio_net__init(struct kvm *kvm)
>  
>  	if (kvm->cfg.num_net_devices == 0 && kvm->cfg.no_net == 0) {
>  		static struct virtio_net_params net_params;
> +		pr_warning(
> +			"No net devices configured, but no_net not specified. "
> +			"Enabling virtio_net with default network settings...\n");

I am a bit unsure about it. We recently tried to get rid of those molly
guard messages, so I am not sure we should issue a *warning* here. After
all, nothing is wrong, it's documented behaviour.

Cheers,
Andre

>  
>  		net_params = (struct virtio_net_params) {
>  			.guest_ip	= kvm->cfg.guest_ip,