[Xen-devel] [PATCH RFC 1/4] libxl: add a list of abstract 'channels' to the domain config

[David Scott <dave.scott@xxxxxxxxxx>]

A 'channel' is a low-bandwidth private communication channel that
resembles a physical serial port. Example uses include:

  * providing initial VM configuration without having to use the
    network
  * signalling a guest agent

Every channel has a string 'name' which the VM can use to find
the appropriate handler. Each channel has an implementation 'type'
which currently includes:

  * NONE: reads will block, writes will be thrown away
  * PTY: the I/O surfaces as a pty in the backend domain
  * PATH: writes are appended to a log file in the backend domain
  * SOCKET: a listening Unix domain socket accepts a connection in
    the backend domain and proxies

Signed-off-by: David Scott <dave.scott@xxxxxxxxxx>
---
 tools/libxl/libxl_types.idl |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 52f1aa9..4df8d42 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -51,6 +51,17 @@ libxl_domain_type = Enumeration("domain_type", [
     (2, "PV"),
     ], init_val = -1)
 
+libxl_channel_type = Enumeration("channel_type", [
+    # Connected to nothing:
+    (0, "NONE"),
+    # Connect to a pty in the backend domain:
+    (1, "PTY"),
+    # Spool output to a file in the backend domain:
+    (2, "PATH"),
+    # Listen on a Unix domain socket in the backend domain:
+    (3, "SOCKET"),
+    ], init_val = 0)
+
 libxl_device_model_version = Enumeration("device_model_version", [
     (0, "UNKNOWN"),
     (1, "QEMU_XEN_TRADITIONAL"), # Historical qemu-xen device model (qemu-dm)
@@ -457,6 +468,15 @@ libxl_device_vtpm = Struct("device_vtpm", [
     ("uuid",             libxl_uuid),
 ])
 
+libxl_device_channel = Struct("device_channel", [
+    ("backend_domid", libxl_domid),
+    ("backend_domname", string),
+    ("devid", libxl_devid),
+    ("name", string),
+    ("type", libxl_channel_type),
+    ("path", string),
+])
+
 libxl_domain_config = Struct("domain_config", [
     ("c_info", libxl_domain_create_info),
     ("b_info", libxl_domain_build_info),
@@ -467,6 +487,7 @@ libxl_domain_config = Struct("domain_config", [
     ("vfbs", Array(libxl_device_vfb, "num_vfbs")),
     ("vkbs", Array(libxl_device_vkb, "num_vkbs")),
     ("vtpms", Array(libxl_device_vtpm, "num_vtpms")),
+    ("channels", Array(libxl_device_channel, "num_channels")),
 
     ("on_poweroff", libxl_action_on_shutdown),
     ("on_reboot", libxl_action_on_shutdown),
-- 
1.7.10.4


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