qcow2: skip writing zero buffers to empty COW areas

[qemu.git] / qapi / trace.json

# -*- mode: python -*-
#
# Copyright (C) 2011-2016 Lluís Vilanova <[email protected]>
#
# 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'} }