[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: RE: [PATCH] virtio-net: Define configuration field layout before its description
> From: Michael S. Tsirkin <mst@redhat.com> > Sent: Tuesday, February 7, 2023 4:58 PM > > On Tue, Feb 07, 2023 at 09:33:11PM +0000, Parav Pandit wrote: > > > > > > > From: Cornelia Huck <cohuck@redhat.com> > > > Sent: Tuesday, February 7, 2023 10:50 AM > > > > > > On Tue, Feb 07 2023, Parav Pandit <parav@nvidia.com> wrote: > > > > > > >> From: Cornelia Huck <cohuck@redhat.com> > > > >> Sent: Tuesday, February 7, 2023 8:49 AM > > > >> > > > >> On Fri, Feb 03 2023, Parav Pandit <parav@nvidia.com> wrote: > > > >> > > > >> > Currently some fields of the virtio_net_config structure are > > > >> > defined before introducing the structure and some are defined > > > >> > after introducing virtio_net_config. > > > >> > Better to define the configuration layout first followed by > > > >> > description of all the fields. > > > >> > > > >> I see that some other devices (e.g. block) list the config layout > > > >> _after_ all of the descriptions, although I think listing first > > > >> and then describing is the better approach. However, in-between > > > >> is the worst order, and just cleaning up this one right now makes sense. > > > >> > > > > Yes. block can be improved too. > > > > I will send separate patch for block side later. > > > > > > I think there were one or two others; but I consider none of this > > > urgent > > > :) > > > > > o.k. > > Will look into it. > > > > > > > > > >> > > > > >> > Device configuration fields are described in the section. > > > >> > Change wording from 'listed' to 'described' as suggested in patch [1]. > > > >> > > > > >> > [1] > > > >> > https://lists.oasis-open.org/archives/virtio-dev/202302/msg0000 > > > >> > 4.ht > > > >> > ml > > > >> > > > > >> > Signed-off-by: Parav Pandit <parav@nvidia.com> > > > >> > --- > > > >> > device-types/net/description.tex | 39 > > > >> > +++++++++++++++++--------------- > > > >> > 1 file changed, 21 insertions(+), 18 deletions(-) > > > >> > > > > >> > diff --git a/device-types/net/description.tex > > > >> > b/device-types/net/description.tex > > > >> > index dedd6b1..d4f598b 100644 > > > >> > --- a/device-types/net/description.tex > > > >> > +++ b/device-types/net/description.tex > > > >> > @@ -154,11 +154,27 @@ \subsubsection{Legacy Interface: Feature > > > >> > bits}\label{sec:Device Types / Network \subsection{Device > > > >> > configuration layout}\label{sec:Device Types / Network Device / > > > >> > Device configuration layout} \label{sec:Device Types / Block > > > >> > Device / Feature bits / Device configuration layout} > > > >> > > > > >> > -Device configuration fields are listed below, they are > > > >> > read-only for a driver. The \field{mac} address field -always > > > >> > exists (though is only valid if VIRTIO_NET_F_MAC is set), and > > > >> > -\field{status} only exists if VIRTIO_NET_F_STATUS is set. Two > > > >> > -read-only bits (for the > > > >> > driver) are > > > >> currently defined for the status field: > > > >> > -VIRTIO_NET_S_LINK_UP and VIRTIO_NET_S_ANNOUNCE. > > > >> > +Device configuration fields are described below, they are > > > >> > +read-only for a > > > >> driver. > > > >> > > > >> Maybe replace that with: > > > >> > > > >> "The network device uses the following device configuration layout. > > > >> The fields are read-only for the driver." > > > >> > > > > I want to avoid "uses" term. Because it is the device > > > > configuration layout built > > > in the device. > > > > How about, > > > > The network device has the following device configuration layout. > > > > > > Works for me. > > > > > Ok. > > > > > > > > > >> > + > > > >> > +\begin{lstlisting} > > > >> > +struct virtio_net_config { > > > >> > + u8 mac[6]; > > > >> > + le16 status; > > > >> > + le16 max_virtqueue_pairs; > > > >> > + le16 mtu; > > > >> > + le32 speed; > > > >> > + u8 duplex; > > > >> > + u8 rss_max_key_size; > > > >> > + le16 rss_max_indirection_table_length; > > > >> > + le32 supported_hash_types; }; \end{lstlisting} > > > >> > + > > > >> > +The \field{mac} address field always exists (though is only > > > >> > +valid if VIRTIO_NET_F_MAC is set), and \field{status} only > > > >> > +exists if VIRTIO_NET_F_STATUS is set. Two read-only bits (for > > > >> > +the driver) are currently defined for the status field: > > > >> > +VIRTIO_NET_S_LINK_UP and VIRTIO_NET_S_ANNOUNCE. > > > >> > > > >> As you are touching this anyway, maybe break it up? > > > >> > > > >> "The \field{mac} address field always exists (although it is only > > > >> valid if VIRTIO_NET_F_MAC is set). > > > >> > > > > I want to avoid such change in this patch. > > > > > > This is only splitting up the sentence and tweaking the grammar, > > > which I consider a rather minor change. > > > > > > > This whole section about "exist" is very confusing. Because > > > > structure layout is > > > not going to change when field don't "exist". But that is counter > > > intuitive for the term "exist". > > > > And hence the "exist" wording is incorrect. > > > > > > I think we have been through that discussion before... would need to > > > look through the archives. > > > > > > > The size of the configuration layout is totally defined by the transport. > > > > > > No, the transport only defines how the config is accessed? > > > > > VIRTIO_PCI_CAP_DEVICE_CFG for PCI and length field in virtio_pci_cap tells > how big the config layout. > > There's explicit text in the spec saying this can be larger than necessary. So > length there does not indicate field existence at all. > It can be larger but has to be minimum upto the length that accommodate the published features bits.
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]