[dpdk-dev] [PATCH 1/3] doc: update vhost programming guide
yuanhan.liu at linux.intel.com
Wed Nov 2 04:14:59 CET 2016
vhost-cuse has been removed in this release. Update the doc, with the
vhost-cuse part being removed.
Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
doc/guides/prog_guide/vhost_lib.rst | 62 +++++--------------------------------
1 file changed, 7 insertions(+), 55 deletions(-)
diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 573a318..4f997d4 100644
@@ -46,26 +46,8 @@ vhost library should be able to:
* Know all the necessary information about the vring:
Information such as where the available ring is stored. Vhost defines some
- messages to tell the backend all the information it needs to know how to
- manipulate the vring.
-Currently, there are two ways to pass these messages and as a result there are
-two Vhost implementations in DPDK: *vhost-cuse* (where the character devices
-are in user space) and *vhost-user*.
-Vhost-cuse creates a user space character device and hook to a function ioctl,
-so that all ioctl commands that are sent from the frontend (QEMU) will be
-captured and handled.
-Vhost-user creates a Unix domain socket file through which messages are
- Since DPDK v2.2, the majority of the development effort has gone into
- enhancing vhost-user, such as multiple queue, live migration, and
- reconnect. Thus, it is strongly advised to use vhost-user instead of
+ messages (passed through a Unix domain socket file) to tell the backend all
+ the information it needs to know how to manipulate the vring.
Vhost API Overview
@@ -75,11 +57,10 @@ The following is an overview of the Vhost API functions:
* ``rte_vhost_driver_register(path, flags)``
- This function registers a vhost driver into the system. For vhost-cuse, a
- ``/dev/path`` character device file will be created. For vhost-user server
- mode, a Unix domain socket file ``path`` will be created.
+ This function registers a vhost driver into the system. ``path`` specifies
+ the Unix domain socket file path.
- Currently supported flags are (these are valid for vhost-user only):
+ Currently supported flags are:
@@ -171,35 +152,8 @@ The following is an overview of the Vhost API functions:
-When vSwitch registers the vhost driver, it will register a cuse device driver
-into the system and creates a character device file. This cuse driver will
-receive vhost open/release/IOCTL messages from the QEMU simulator.
-When the open call is received, the vhost driver will create a vhost device
-for the virtio device in the guest.
-When the ``VHOST_SET_MEM_TABLE`` ioctl is received, vhost searches the memory
-region to find the starting user space virtual address that maps the memory of
-the guest virtual machine. Through this virtual address and the QEMU pid,
-vhost can find the file QEMU uses to map the guest memory. Vhost maps this
-file into its address space, in this way vhost can fully access the guest
-physical memory, which means vhost could access the shared virtio ring and the
-guest physical address specified in the entry of the ring.
-The guest virtual machine tells the vhost whether the virtio device is ready
-for processing or is de-activated through the ``VHOST_NET_SET_BACKEND``
-message. The registered callback from vSwitch will be called.
-When the release call is made, vhost will destroy the device.
Vhost-user uses Unix domain sockets for passing messages. This means the DPDK
vhost-user implementation has two options:
@@ -246,8 +200,6 @@ For ``VHOST_SET_MEM_TABLE`` message, QEMU will send information for each
memory region and its file descriptor in the ancillary data of the message.
The file descriptor is used to map that region.
-There is no ``VHOST_NET_SET_BACKEND`` message as in vhost-cuse to signal
-whether the virtio device is ready or stopped. Instead,
``VHOST_SET_VRING_KICK`` is used as the signal to put the vhost device into
the data plane, and ``VHOST_GET_VRING_BASE`` is used as the signal to remove
the vhost device from the data plane.
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