From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 12 Aug 2022 13:19:25 -0400 From: "Michael S. Tsirkin" Subject: [PATCH RFC v7 7/8] admin: document that structures can be shorter or longer Message-ID: <20220812171841.12183-8-mst@redhat.com> References: <20220812171841.12183-1-mst@redhat.com> MIME-Version: 1.0 In-Reply-To: <20220812171841.12183-1-mst@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline To: virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org, jasowang@redhat.com, mst@redhat.com, cohuck@redhat.com, sgarzare@redhat.com, stefanha@redhat.com, nrupal.jani@intel.com, Piotr.Uminski@intel.com, hang.yuan@intel.com Cc: virtio@lists.oasis-open.org, Zhu Lingshan , oren@nvidia.com, parav@nvidia.com, shahafs@nvidia.com, aadam@redhat.com, eperezma@redhat.com, Max Gurtovoy List-ID: ensures forward and backward compatibility as long as we tuck new structures at the end. Signed-off-by: Michael S. Tsirkin --- admin.tex | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/admin.tex b/admin.tex index a0008c7..99b6c2a 100644 --- a/admin.tex +++ b/admin.tex @@ -136,6 +136,12 @@ \subsection{Group administration commands}\label{sec:Basic Facilities of a Virti holds the command specific error. If \field{status} is not set to VIRTIO_ADMIN_STATUS_CS_ERR, the \field{command_specific_error} value is undefined and should be ignored by the driver. +It is legal for the driver to submit commands with device-writeable and +device-readable structures both shorter and longer than what +is described in this specification. Device silently truncates the +structures to the shorter of the two (submitted by driver and +described in this specification). + \section{Administration Virtqueue}\label{sec:Basic Facilities of a Virtio Device / Group Administration Virtqueues} An administration virtqueue of a parent device is used to submit -- MST