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authormstsirkin <mstsirkin@0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652>2014-12-23 19:28:10 +0000
committermstsirkin <mstsirkin@0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652>2014-12-23 19:28:10 +0000
commit0be6c18bce52e3b0bcfcf087a163b975bede8c23 (patch)
tree62e82eab2bc59a89c2d0fefc28dd00b5a155f7b1 /feedback/6.txt
parent0ebeb90b133d201bc3354c5fe525ddc9559bd5bb (diff)
feedback: drop unused feedback files
So that we don't need to remove them manually. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> git-svn-id: https://tools.oasis-open.org/version-control/svn/virtio/branches/v1.0@465 0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652
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-Document: virtio-v1.0-csprd01
-Number: 6
-Date: Wed, 29 Jan 2014 21:36:30 +0100
-Link to Mail: https://lists.oasis-open.org/archives/virtio-comment/201401/msg00055.html
-Commenter name: Thomas Huth <thuth@linux.vnet.ibm.com>
-Decision: 2014-02-11 minutes: Applied
-
-Generic remark: Quite a lot of structures use a mixture of "u8"
-and "char" types for bytes, e.g. struct virtio_blk_req. Is that
-intended? If not, I'd suggest to always use "u8" here instead.
-
-
-Page 38 / Device Types:
-
-Is the information about other virtio devices like 9P documented
-somewhere else? If yes, you might want to put a pointer to these
-documents here.
-
-
-Page 43 and page 44:
-
-Some of the #defines are indented with an additional space.
-That looks a little bit ugly, would be great if you could get rid
-of the indentation here.
-
-
-Page 43 / Setting MAC Address Filtering
-
-ETH_ALEN is a Linux-internal #define only, which is not defined
-in this spec, so I'd suggest to simply replace ETH_ALEN with 6 here.
-
-
-Page 48 / Virtqueues
-
-The initial numbered list names the second pair of console virtqueues
-"port1" but the next sentence talks about "Port 2" ... that's confusing.
-==> Maybe replace "Ports 2 onwards only exist ..." with something like
-"All ports except the first one only exist ..." ?
-
-
-Page 50:
-
-The paragraph "5." says:
-"If the device specified a port `name', a sysfs attribute is created with
-the name filled in, so that udev rules can be written that can create a
-symlink from the port's name to the char device for port discovery by
-applications in the driver."
-==> That's completely specific to Linux as far as I can tell, so I think
-this should not go into a generic specification document, or at least it
-should be marked as an example for Linux.
-Also, this paragraph talks about the "name" which is not introduced before
-paragraph "6.", so I think if you really want to keep this paragraph "5.",
-it should be moved behind "6." instead.
-
-Concerning paragraph "6.":
-The console port change events are hardly documented ... I think this
-paragraph needs some love. How does the "value" look like for the
-various message types? For example, how is the size of the console
-passed when the VIRTIO_CONSOLE_RESIZE event occured? Or the name? What
-is the difference between VIRTIO_CONSOLE_PORT_ADD and
-VIRTIO_CONSOLE_PORT_OPEN?
-
-As a further remark, I also I wonder whether should be a way to signal
-the terminal type (like "vt100") to the guest?
-
-
-Page 55 / Device Operation: Request Queues
-
-While reading this chapter, I first got a little bit confused about the
-terms "read-only" and "write-only" since I read chapter 4.1.3.1.1
-("Virtio Device Configuration Layout Detection") shortly before, where
-the terms are used in the opposite way - since "read-only" and
-"write-only" are dependend on the view, whether you talk about the device
-or the driver.
-So even it's clear when you read the various chapters twice and think
-about everything logically, it might be more consisten and easier to
-read if you always say something more explicit like "read-only for the
-device" or "read-only for the driver" throughout the specification.
-
-Proposal:
-
-diff --git a/content.tex b/content.tex
-index 7e77740..27a957d 100644
---- a/content.tex
-+++ b/content.tex
-@@ -286,7 +286,7 @@ struct vring {
- struct vring_avail avail;
-
- // Padding to the next PAGE_SIZE boundary.
-- char pad[ Padding ];
-+ u8 pad[ Padding ];
-
- // A ring of used descriptor heads with free-running index.
- struct vring_used used;
-@@ -334,8 +334,11 @@ VIRTIO_F_ANY_LAYOUT feature is accepted.
- The descriptor table refers to the buffers the driver is using for
- the device. The addresses are physical addresses, and the buffers
- can be chained via the next field. Each descriptor describes a
--buffer which is read-only or write-only, but a chain of
--descriptors can contain both read-only and write-only buffers.
-+buffer which is read-only for the device (``device-readable'') or write-only for the device (``device-writable''), but a chain of
-+descriptors can contain both device-readable and device-writable buffers.
-+A device MUST NOT write to a device-readable buffer, and a device SHOULD NOT
-+read a device-writable buffer (it might do so for debugging or diagnostic
-+purposes).
-
- The actual contents of the memory offered to the device depends on the
- device type. Most common is to begin the data with a header
-@@ -355,7 +358,7 @@ struct vring_desc {
-
- /* This marks a buffer as continuing via the next field. */
- #define VRING_DESC_F_NEXT 1
--/* This marks a buffer as write-only (otherwise read-only). */
-+/* This marks a buffer as device write-only (otherwise device read-only). */
- #define VRING_DESC_F_WRITE 2
- /* This means the buffer contains a list of buffer descriptors. */
- #define VRING_DESC_F_INDIRECT 4
-@@ -401,7 +404,7 @@ chained by next field. An indirect descriptor without next field
- An
- indirect descriptor can not refer to another indirect descriptor
- table (flags\&VRING_DESC_F_INDIRECT MUST be off). A single indirect descriptor
--table can include both read-only and write-only descriptors;
-+table can include both device-readable and device-writable descriptors;
- the device MUST ignore the write-only flag (flags\&VRING_DESC_F_WRITE) in the descriptor that refers to it.
-
- \subsection{The Virtqueue Available Ring}\label{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Available Ring}
-@@ -575,8 +578,8 @@ There are two parts to device operation: supplying new buffers to
- the device, and processing used buffers from the device. As an
- example, the simplest virtio network device has two virtqueues: the
- transmit virtqueue and the receive virtqueue. The driver adds
--outgoing (read-only) packets to the transmit virtqueue, and then
--frees them after they are used. Similarly, incoming (write-only)
-+outgoing (device-readable) packets to the transmit virtqueue, and then
-+frees them after they are used. Similarly, incoming (device-writable)
- buffers are added to the receive virtqueue, and processed after
- they are used.
-
-@@ -621,9 +624,9 @@ Here is a description of each stage in more detail.
-
- \subsubsection{Placing Buffers Into The Descriptor Table}\label{sec:General Initialization And Device Operation / Device Operation / Supplying Buffers to The Device / Placing Buffers Into The Descriptor Table}
-
--A buffer consists of zero or more read-only physically-contiguous
-+A buffer consists of zero or more device-readable physically-contiguous
- elements followed by zero or more physically-contiguous
--write-only elements (it must have at least one element). This
-+device-writable elements (it must have at least one element). This
- algorithm maps it into the descriptor table to form a descriptor
- chain:
-
-@@ -633,7 +636,7 @@ for each buffer element, b:
- \item Get the next free descriptor table entry, d
- \item Set d.addr to the physical address of the start of b
- \item Set d.len to the length of b.
--\item If b is write-only, set d.flags to VRING_DESC_F_WRITE,
-+\item If b is device-writable, set d.flags to VRING_DESC_F_WRITE,
- otherwise 0.
- \item If there is a buffer element after this:
- \begin{enumerate}
-@@ -708,7 +711,7 @@ notification:
-
- \subsection{Receiving Used Buffers From The Device}\label{sec:General Initialization And Device Operation / Device Operation / Receiving Used Buffers From The Device}
-
--Once the device has used a buffer (read from or written to it, or
-+Once the device has used buffers referred to by a descriptor (read from or written to them, or
- parts of both, depending on the nature of the virtqueue and the
- device), it SHOULD send an interrupt, following an algorithm very
- similar to the algorithm used for the driver to send the device a
-@@ -835,7 +838,7 @@ the function, or accessed via the special VIRTIO_PCI_CAP_PCI_CFG field in the PC
- The location of each structure is specified using a vendor-specific PCI capability located
- on the capability list in PCI configuration space of the device.
- This virtio structure capability uses little-endian format; all fields are
--read-only unless stated otherwise:
-+read-only for the driver unless stated otherwise:
-
- \begin{lstlisting}
- struct virtio_pci_cap {
-@@ -946,20 +949,20 @@ The device MUST present at least one common configuration capability.
- struct virtio_pci_common_cfg {
- /* About the whole device. */
- le32 device_feature_select; /* read-write */
-- le32 device_feature; /* read-only */
-+ le32 device_feature; /* read-only for driver */
- le32 driver_feature_select; /* read-write */
- le32 driver_feature; /* read-write */
- le16 msix_config; /* read-write */
-- le16 num_queues; /* read-only */
-+ le16 num_queues; /* read-only for driver */
- u8 device_status; /* read-write */
-- u8 config_generation; /* read-only */
-+ u8 config_generation; /* read-only for driver */
-
- /* About a specific virtqueue. */
- le16 queue_select; /* read-write */
- le16 queue_size; /* read-write, power of 2, or 0. */
- le16 queue_msix_vector; /* read-write */
- le16 queue_enable; /* read-write */
-- le16 queue_notify_off; /* read-only */
-+ le16 queue_notify_off; /* read-only for driver */
- le64 queue_desc; /* read-write */
- le64 queue_avail; /* read-write */
- le64 queue_used; /* read-write */
-@@ -2351,6 +2354,13 @@ Device ID & Virtio Device \\
- \hline
- \end{tabular}
-
-+Some of the devices above are unspecified by this document,
-+because they are seen as immature or especially niche. Be warned
-+that they may only be specified by the sole existing implementation;
-+they may become part of a future specification, be abandoned
-+entirely, or live on outside this standard. We shall speak of
-+them no further.
-+
- \section{Network Device}\label{sec:Device Types / Network Device}
-
- The virtio network device is a virtual ethernet card, and is the
-@@ -2445,7 +2455,7 @@ were required.
- Three configuration fields are currently defined. The mac address field
- always exists (though is only valid if VIRTIO_NET_F_MAC is set), and
- the status field only exists if VIRTIO_NET_F_STATUS is set. Two
--read-only bits are currently defined for the status field:
-+read-only bits (for the driver) are currently defined for the status field:
- VIRTIO_NET_S_LINK_UP and VIRTIO_NET_S_ANNOUNCE.
-
- \begin{lstlisting}
-@@ -2453,7 +2463,7 @@ VIRTIO_NET_S_LINK_UP and VIRTIO_NET_S_ANNOUNCE.
- #define VIRTIO_NET_S_ANNOUNCE 2
- \end{lstlisting}
-
--The following read-only field, max_virtqueue_pairs only exists if
-+The following driver-read-only field, max_virtqueue_pairs only exists if
- VIRTIO_NET_F_MQ is set. This field specifies the maximum number
- of each of transmit and receive virtqueues (receiveq0..receiveqN
- and transmitq0..transmitqN respectively;
-@@ -2764,7 +2774,7 @@ off. The command-specific-data is one byte containing 0 (off) or
- \begin{lstlisting}
- struct virtio_net_ctrl_mac {
- le32 entries;
-- u8 macs[entries][ETH_ALEN];
-+ u8 macs[entries][6];
- };
-
- #define VIRTIO_NET_CTRL_MAC 1
-@@ -2786,7 +2796,7 @@ When VIRTIO_NET_F_MAC_ADDR is not negotiated, the mac field in
- config space is writeable and is used to set the default MAC
- address which rx filtering accepts.
- When VIRTIO_NET_F_MAC_ADDR is negotiated, the mac field in
--config space becomes read-only.
-+config space becomes read-only for the driver.
- The VIRTIO_NET_CTRL_MAC_ADDR_SET command is used to set the
- default MAC address which rx filtering
- accepts
-@@ -3090,7 +3100,7 @@ struct virtio_blk_req {
- le32 type;
- le32 reserved;
- le64 sector;
-- char data[][512];
-+ u8 data[][512];
- u8 status;
- };
- \end{lstlisting}
-@@ -3155,8 +3165,8 @@ struct virtio_scsi_pc_req {
- u32 type;
- u32 ioprio;
- u64 sector;
-- char cmd[];
-- char data[][512];
-+ u8 cmd[];
-+ u8 data[][512];
- #define SCSI_SENSE_BUFFERSIZE 96
- u8 sense[SCSI_SENSE_BUFFERSIZE];
- u32 errors;
-@@ -3178,12 +3188,12 @@ does not distinguish between them:
-
- The cmd field is only present for scsi packet command requests,
- and indicates the command to perform. This field must reside in a
--single, separate read-only buffer; command length can be derived
-+single, separate device-readable buffer; command length can be derived
- from the length of this buffer.
-
- Note that these first three (four for scsi packet commands)
--fields are always read-only: the data field is either read-only
--or write-only, depending on the request. The size of the read or
-+fields are always device-readable: the data field is either device-readable
-+or device-writable, depending on the request. The size of the read or
- write can be derived from the total size of the request buffers.
-
- The sense field is only present for scsi packet command requests,
-@@ -3202,12 +3212,12 @@ requests and indicates the residual size, calculated as data
- length - number of bytes actually transferred.
-
- Historically, devices assumed that the fields type, ioprio and
--sector reside in a single, separate read-only buffer; the fields
-+sector reside in a single, separate device-readable buffer; the fields
- errors, data_len, sense_len and residual reside in a single,
--separate write-only buffer; the sense field in a separate
--write-only buffer of size 96 bytes, by itself; the fields errors,
--data_len, sense_len and residual in a single write-only buffer;
--and the status field is a separate write-only buffer of size 1
-+separate device-writable buffer; the sense field in a separate
-+device-writable buffer of size 96 bytes, by itself; the fields errors,
-+data_len, sense_len and residual in a single device-writable buffer;
-+and the status field is a separate device-writable buffer of size 1
- byte, by itself.
-
-
-@@ -3242,7 +3252,8 @@ data and outgoing characters are placed in the transmit queue.
- \item[\ldots]
- \end{description}
-
-- Ports 2 onwards only exist if VIRTIO_CONSOLE_F_MULTIPORT is set.
-+The port 0 receive and transmit queues always exist: other queues
-+only exist if VIRTIO_CONSOLE_F_MULTIPORT is set.
-
- \subsection{Feature bits}\label{sec:Device Types / Console Device / Feature bits}
-
-@@ -3305,7 +3316,7 @@ native endian of the guest rather than (necessarily) little-endian.
- control messages for adding new ports to the device. After
- creating and initializing each port, a
- VIRTIO_CONSOLE_PORT_READY control message is sent to the device
-- for that port so the device can let us know of any additional
-+ for that port so the device can let the driver know of any additional
- configuration options set for that port.
-
- \item The receiveq for each port is populated with one or more
-@@ -3331,22 +3342,21 @@ when a port is closed or hot-unplugged.
-
- \item If the driver negotiated the VIRTIO_CONSOLE_F_SIZE feature, a
- configuration change interrupt may occur. The updated size can
-- be read from the configuration fields.
-+ be read from the configuration fields. This size applies to port 0 only.
-
- \item If the driver negotiated the VIRTIO_CONSOLE_F_MULTIPORT
- feature, active ports are announced by the device using the
- VIRTIO_CONSOLE_PORT_ADD control message. The same message is
- used for port hot-plug as well.
-+\end{enumerate}
-
--\item If the device specified a port `name', a sysfs attribute is
-- created with the name filled in, so that udev rules can be
-- written that can create a symlink from the port's name to the
-- char device for port discovery by applications in the driver.
-+\subsubsection{Multiport Device Operation}\label{sec:Device Types / Console Device / Device Operation / Multiport Device Operation}
-
--\item Changes to ports' state are effected by control messages.
-- Appropriate action is taken on the port indicated in the
-- control message. The layout of the structure of the control
-- buffer and the events associated are:
-+If the driver negotiated the VIRTIO_CONSOLE_F_MULTIPORT, the two
-+control queues are used to manipulate the different console ports: the
-+control receiveq for messages from the device to the driver, and the
-+control sendq for driver-to-device messages. The layout of the
-+control messages is:
-
- \begin{lstlisting}
- /* Note: LEGACY version was not little endian! */
-@@ -3355,18 +3365,45 @@ struct virtio_console_control {
- le16 event; /* The kind of control event */
- le16 value; /* Extra information for the event */
- };
-+\end{lstlisting}
-
--/* Some events for the internal messages (control packets) */
--#define VIRTIO_CONSOLE_DEVICE_READY 0
--#define VIRTIO_CONSOLE_PORT_ADD 1
--#define VIRTIO_CONSOLE_PORT_REMOVE 2
--#define VIRTIO_CONSOLE_PORT_READY 3
--#define VIRTIO_CONSOLE_CONSOLE_PORT 4
--#define VIRTIO_CONSOLE_RESIZE 5
--#define VIRTIO_CONSOLE_PORT_OPEN 6
--#define VIRTIO_CONSOLE_PORT_NAME 7
-+The values for \field{event} are:
-+\begin{description}
-+\item [VIRTIO_CONSOLE_DEVICE_READY (0)] Sent by the driver at initialization
-+ to indicate that it is ready to receive control messages. A value of
-+ 1 indicates success, and 0 indicates failure. The port number is unused.
-+\item [VIRTIO_CONSOLE_DEVICE_ADD (1)] Sent by the device, to create a new
-+ port. The device MUST NOT specify a port which exists. \field{value} is unused.
-+\item [VIRTIO_CONSOLE_DEVICE_REMOVE (2)] Sent by the device, to remove an
-+ existing port. The device MUST NOT specify a port which has not been
-+ created with VIRTIO_CONSOLE_DEVICE_ADD. \field{value} is unused.
-+\item [VIRTIO_CONSOLE_PORT_READY (3)] Sent by the driver in response
-+ to the device's VIRTIO_CONSOLE_PORT_ADD message, to indicate that
-+ the port is ready to be used. A \field{value} of 1 indicates success, and 0
-+ indicates failure.
-+\item [VIRTIO_CONSOLE_CONSOLE_PORT (4)] Sent by the device to nominate
-+ a port as a console port. There may be more than one console port.
-+ The driver SHOULD treat the port in a manner suitable for text
-+ console access; the driver MUST respond with a VIRTIO_CONSOLE_PORT_OPEN
-+ message. The driver MUST set \field{value} to 1.
-+\item [VIRTIO_CONSOLE_RESIZE (5)] Sent by the device to indicate
-+ a console size change. \field{value} is unused. The buffer is followed by the number of columns and rows:
-+\begin{lstlisting}
-+struct virtio_console_resize {
-+ le16 cols;
-+ le16 rows;
-+};
- \end{lstlisting}
--\end{enumerate}
-+\item [VIRTIO_CONSOLE_PORT_OPEN (6)] This message is sent by both the
-+ device and the driver. \field{value} MUST BE set to 0 (port
-+ closed) or 1 (port open). This allows for ports to be used directly
-+ by guest and host processes to communicate in an application-defined
-+ manner.
-+\item [VIRTIO_CONSOLE_PORT_NAME (7)] Sent by the device to give a tag
-+ to the port. This control command is immediately
-+ followed by the UTF-8 name of the port for identification
-+ within the guest (without a NUL terminator).
-+\end{description}
-
- \subsubsection{Legacy Interface: Device Operation}\label{sec:Device Types / Console Device / Device Operation / Legacy Interface: Device Operation}
- For legacy devices, the fields in struct virtio_console_control are the
-@@ -3616,7 +3653,7 @@ targets that receive and process the requests.
-
- \begin{description}
- \item[VIRTIO_SCSI_F_INOUT (0)] A single request can include both
-- read-only and write-only data buffers.
-+ device-readable and device-writable data buffers.
-
- \item[VIRTIO_SCSI_F_HOTPLUG (1)] The host should enable
- hot-plug/hot-unplug of new LUNs and targets on the SCSI bus.
-@@ -3718,22 +3755,22 @@ Requests have the following format:
- \begin{lstlisting}
- /* Note: LEGACY version was not little endian! */
- struct virtio_scsi_req_cmd {
-- // Read-only
-+ // Device-readable part
- u8 lun[8];
- le64 id;
- u8 task_attr;
- u8 prio;
- u8 crn;
-- char cdb[cdb_size];
-- char dataout[];
-- // Write-only part
-+ u8 cdb[cdb_size];
-+ u8 dataout[];
-+ // Device-writable part
- le32 sense_len;
- le32 residual;
- le16 status_qualifier;
- u8 status;
- u8 response;
- u8 sense[sense_size];
-- char datain[];
-+ u8 datain[];
- };
-
-
-@@ -3774,10 +3811,10 @@ value defined by the protocol is 255, since CRN is stored in an
- 8-bit integer.
-
- All of these fields are defined in SAM. They are always
--read-only, as are the cdb and dataout field. The cdb_size is
-+device-readable, as are the cdb and dataout field. The cdb_size is
- taken from the configuration space.
-
--sense and subsequent fields are always write-only. The sense_len
-+sense and subsequent fields are always device-writable. The sense_len
- field indicates the number of bytes actually written to the sense
- buffer. The residual field indicates the residual size,
- calculated as “data_length - number_of_transferred_bytes”, for
-@@ -3880,12 +3917,12 @@ The following commands are defined:
- /* Note: LEGACY version was not little endian! */
- struct virtio_scsi_ctrl_tmf
- {
-- // Read-only part
-+ // Device-readable part
- le32 type;
- le32 subtype;
- u8 lun[8];
- le64 id;
-- // Write-only part
-+ // Device-writable part
- u8 response;
- }
-
-@@ -3917,11 +3954,11 @@ struct virtio_scsi_ctrl_tmf
- #define VIRTIO_SCSI_T_AN_QUERY 1
-
- struct virtio_scsi_ctrl_an {
-- // Read-only part
-+ // Device-readable part
- le32 type;
- u8 lun[8];
- le32 event_requested;
-- // Write-only part
-+ // Device-writable part
- le32 event_actual;
- u8 response;
- }
-@@ -3952,11 +3989,11 @@ struct virtio_scsi_ctrl_an {
- #define VIRTIO_SCSI_T_AN_SUBSCRIBE 2
-
- struct virtio_scsi_ctrl_an {
-- // Read-only part
-+ // Device-readable part
- le32 type;
- u8 lun[8];
- le32 event_requested;
-- // Write-only part
-+ // Device-writable part
- le32 event_actual;
- u8 response;
- }
-@@ -3999,7 +4036,7 @@ should be enough.
-
- Buffers are placed in the eventq and filled by the device when
- interesting events occur. The buffers should be strictly
--write-only (device-filled) and the size of the buffers should be
-+device-writable and the size of the buffers should be
- at least the value given in the device's configuration
- information.
-
-@@ -4011,7 +4048,7 @@ following format:
- #define VIRTIO_SCSI_T_EVENTS_MISSED 0x80000000
-
- struct virtio_scsi_event {
-- // Write-only part
-+ // Device-writable part
- le32 event;
- u8 lun[8];
- le32 reason;
-@@ -4232,13 +4269,13 @@ transmit output.
-
- Configuration space should only be used for initialization-time
- parameters. It is a limited resource with no synchronization between
--writable fields, so for most uses it is better to use a virtqueue to update
-+field written by the driver, so for most uses it is better to use a virtqueue to update
- configuration information (the network device does this for filtering,
- otherwise the table in the config space could potentially be very
- large).
-
- Devices must not assume that configuration fields over 32 bits wide
--are atomically writable.
-+are atomically writable by the driver.
-
- \section{What Device Number?}\label{sec:Creating New Device Types / What Device Number?}
-