Re: [virtio-comment] [PATCH] virtio-vsock: add max payload size config field

[Stefan Hajnoczi <stefanha@redhat.com>]

On Mon, Apr 04, 2022 at 04:49:31PM +0300, Laura Loghin wrote:
> @@ -57,6 +62,35 @@ \subsection{Device configuration layout}\label{sec:Device Types / Socket Device
>  \hline
>  \end{tabular}
>  
> +The following driver-read-only field, \field{data_max_size} only exists if
> +VIRTIO_VSOCK_F_SIZE_MAX is set. This field specifies the maximum packet payload
> +size for the driver to use.

This wording can be misinterpreted but can be kept for now. This wording
should be updated when the next field is added in the future, indicating
that the field is only *used* when VIRTIO_VSOCK_F_SIZE_MAX has been
negotiated. Further fields will be located after data_max_size so the
field certainly *exists* even when VIRTIO_VSOCK_F_SIZE_MAX is not set.

If someone misinterprets this they might think the config struct layout
depends on the combination of negotiated feature bits. That's not the
case, the layout is always the same. The size of the struct depends on
the features offered by the device.

Similar wording is used elsewhere in the spec, so we may want to clarify
it for the entire spec.

Stefan

Attachment: signature.asc
Description: PGP signature