Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 108 insertions, 0 deletions

diff --git a/qapi/trace.json b/qapi/trace.json
new file mode 100644
index 000000000..eedfded51
--- /dev/null
+++ b/qapi/trace.json
@@ -0,0 +1,108 @@
+# -*- mode: python -*-
+#
+# Copyright (C) 2011-2016 Lluís Vilanova <vilanova@ac.upc.edu>
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or later.
+# See the COPYING file in the top-level directory.
+
+##
+# = Tracing
+##
+
+##
+# @TraceEventState:
+#
+# State of a tracing event.
+#
+# @unavailable: The event is statically disabled.
+#
+# @disabled: The event is dynamically disabled.
+#
+# @enabled: The event is dynamically enabled.
+#
+# Since: 2.2
+##
+{ 'enum': 'TraceEventState',
+  'data': ['unavailable', 'disabled', 'enabled'] }
+
+##
+# @TraceEventInfo:
+#
+# Information of a tracing event.
+#
+# @name: Event name.
+# @state: Tracing state.
+# @vcpu: Whether this is a per-vCPU event (since 2.7).
+#
+# An event is per-vCPU if it has the "vcpu" property in the "trace-events"
+# files.
+#
+# Since: 2.2
+##
+{ 'struct': 'TraceEventInfo',
+  'data': {'name': 'str', 'state': 'TraceEventState', 'vcpu': 'bool'} }
+
+##
+# @trace-event-get-state:
+#
+# Query the state of events.
+#
+# @name: Event name pattern (case-sensitive glob).
+# @vcpu: The vCPU to query (any by default; since 2.7).
+#
+# Returns: a list of @TraceEventInfo for the matching events
+#
+#          An event is returned if:
+#
+#          - its name matches the @name pattern, and
+#          - if @vcpu is given, the event has the "vcpu" property.
+#
+#          Therefore, if @vcpu is given, the operation will only match per-vCPU events,
+#          returning their state on the specified vCPU. Special case: if @name is an
+#          exact match, @vcpu is given and the event does not have the "vcpu" property,
+#          an error is returned.
+#
+# Since: 2.2
+#
+# Example:
+#
+# -> { "execute": "trace-event-get-state",
+#      "arguments": { "name": "qemu_memalign" } }
+# <- { "return": [ { "name": "qemu_memalign", "state": "disabled" } ] }
+#
+##
+{ 'command': 'trace-event-get-state',
+  'data': {'name': 'str', '*vcpu': 'int'},
+  'returns': ['TraceEventInfo'] }
+
+##
+# @trace-event-set-state:
+#
+# Set the dynamic tracing state of events.
+#
+# @name: Event name pattern (case-sensitive glob).
+# @enable: Whether to enable tracing.
+# @ignore-unavailable: Do not match unavailable events with @name.
+# @vcpu: The vCPU to act upon (all by default; since 2.7).
+#
+# An event's state is modified if:
+# - its name matches the @name pattern, and
+# - if @vcpu is given, the event has the "vcpu" property.
+#
+# Therefore, if @vcpu is given, the operation will only match per-vCPU events,
+# setting their state on the specified vCPU. Special case: if @name is an exact
+# match, @vcpu is given and the event does not have the "vcpu" property, an
+# error is returned.
+#
+# Since: 2.2
+#
+# Example:
+#
+# -> { "execute": "trace-event-set-state",
+#      "arguments": { "name": "qemu_memalign", "enable": true } }
+# <- { "return": {} }
+#
+##
+{ 'command': 'trace-event-set-state',
+  'data': {'name': 'str', 'enable': 'bool', '*ignore-unavailable': 'bool',
+           '*vcpu': 'int'} }