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Diffstat (limited to 'feedback/3.txt')
| -rw-r--r-- | feedback/3.txt | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/feedback/3.txt b/feedback/3.txt new file mode 100644 index 0000000..961e76e --- /dev/null +++ b/feedback/3.txt @@ -0,0 +1,64 @@ +Document: virtio-v1.0-csprd01 +Number: 3 +Date: Tue, 21 Jan 2014 15:09:54 +0530 +Link to Mail: https://lists.oasis-open.org/archives/virtio-comment/201401/msg00037.html +Commenter name: Pranavkumar Sawargaonkar <pranavkumar@linaro.org> + +This patch updates virtio spec lyx for adding emergency write to +virtio console. + +Original patch series related to this is -: +http://lkml.org/lkml/2013/5/6/167 + +Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org> +Signed-off-by: Anup Patel <anup.patel@linaro.org> +Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> + +Proposal: + +diff --git a/content.tex b/content.tex +index 17d1bd7..96645df 100644 +--- a/content.tex ++++ b/content.tex +@@ -3225,6 +3225,9 @@ data and outgoing characters are placed in the transmit queue. + \item[VIRTIO_CONSOLE_F_MULTIPORT (1)] Device has support for multiple + ports; configuration fields nr_ports and max_nr_ports are + valid and control virtqueues will be used. ++ ++\item[VIRTIO_CONSOLE_F_EMERG_WRITE (2)] Device has support for emergency write. ++ Configuration field emerg_wr is valid. + \end{description} + + \subsection{Device configuration layout}\label{sec:Device Types / Console Device / Device configuration layout} +@@ -3235,11 +3238,16 @@ data and outgoing characters are placed in the transmit queue. + is set, the maximum number of ports supported by the device can + be fetched. + ++ If VIRTIO_CONSOLE_F_EMERG_WRITE is set then the driver can use emergency write ++ to output a single character without initializing virtio queues, or even ++ acknowledging the feature. ++ + \begin{lstlisting} + struct virtio_console_config { + le16 cols; + le16 rows; + le32 max_nr_ports; ++ le32 emerg_wr; + }; + \end{lstlisting} + +@@ -3250,6 +3258,11 @@ native endian of the guest rather than (necessarily) little-endian. + \subsection{Device Initialization}\label{sec:Device Types / Console Device / Device Initialization} + + \begin{enumerate} ++\item If the VIRTIO_CONSOLE_F_EMERG_WRITE feature is offered, the ++ emerg_wr field of the configuration can be written at any time. ++ Thus it should work for very early boot debugging output as well as ++ catastophic OS failures (eg. virtio ring corruption). ++ + \item If the VIRTIO_CONSOLE_F_SIZE feature is negotiated, the driver + can read the console dimensions from the configuration fields. + + +Decision: + |