numa: add -numa node,memdev= option
[qemu.git] / include / qemu / main-loop.h
1 /*
2 * QEMU System Emulator
3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25 #ifndef QEMU_MAIN_LOOP_H
26 #define QEMU_MAIN_LOOP_H 1
27
28 #include "block/aio.h"
29
30 #define SIG_IPI SIGUSR1
31
32 /**
33 * qemu_init_main_loop: Set up the process so that it can run the main loop.
34 *
35 * This includes setting up signal handlers. It should be called before
36 * any other threads are created. In addition, threads other than the
37 * main one should block signals that are trapped by the main loop.
38 * For simplicity, you can consider these signals to be safe: SIGUSR1,
39 * SIGUSR2, thread signals (SIGFPE, SIGILL, SIGSEGV, SIGBUS) and real-time
40 * signals if available. Remember that Windows in practice does not have
41 * signals, though.
42 *
43 * In the case of QEMU tools, this will also start/initialize timers.
44 */
45 int qemu_init_main_loop(void);
46
47 /**
48 * main_loop_wait: Run one iteration of the main loop.
49 *
50 * If @nonblocking is true, poll for events, otherwise suspend until
51 * one actually occurs. The main loop usually consists of a loop that
52 * repeatedly calls main_loop_wait(false).
53 *
54 * Main loop services include file descriptor callbacks, bottom halves
55 * and timers (defined in qemu-timer.h). Bottom halves are similar to timers
56 * that execute immediately, but have a lower overhead and scheduling them
57 * is wait-free, thread-safe and signal-safe.
58 *
59 * It is sometimes useful to put a whole program in a coroutine. In this
60 * case, the coroutine actually should be started from within the main loop,
61 * so that the main loop can run whenever the coroutine yields. To do this,
62 * you can use a bottom half to enter the coroutine as soon as the main loop
63 * starts:
64 *
65 * void enter_co_bh(void *opaque) {
66 * QEMUCoroutine *co = opaque;
67 * qemu_coroutine_enter(co, NULL);
68 * }
69 *
70 * ...
71 * QEMUCoroutine *co = qemu_coroutine_create(coroutine_entry);
72 * QEMUBH *start_bh = qemu_bh_new(enter_co_bh, co);
73 * qemu_bh_schedule(start_bh);
74 * while (...) {
75 * main_loop_wait(false);
76 * }
77 *
78 * (In the future we may provide a wrapper for this).
79 *
80 * @nonblocking: Whether the caller should block until an event occurs.
81 */
82 int main_loop_wait(int nonblocking);
83
84 /**
85 * qemu_get_aio_context: Return the main loop's AioContext
86 */
87 AioContext *qemu_get_aio_context(void);
88
89 /**
90 * qemu_notify_event: Force processing of pending events.
91 *
92 * Similar to signaling a condition variable, qemu_notify_event forces
93 * main_loop_wait to look at pending events and exit. The caller of
94 * main_loop_wait will usually call it again very soon, so qemu_notify_event
95 * also has the side effect of recalculating the sets of file descriptors
96 * that the main loop waits for.
97 *
98 * Calling qemu_notify_event is rarely necessary, because main loop
99 * services (bottom halves and timers) call it themselves. One notable
100 * exception occurs when using qemu_set_fd_handler2 (see below).
101 */
102 void qemu_notify_event(void);
103
104 #ifdef _WIN32
105 /* return TRUE if no sleep should be done afterwards */
106 typedef int PollingFunc(void *opaque);
107
108 /**
109 * qemu_add_polling_cb: Register a Windows-specific polling callback
110 *
111 * Currently, under Windows some events are polled rather than waited for.
112 * Polling callbacks do not ensure that @func is called timely, because
113 * the main loop might wait for an arbitrarily long time. If possible,
114 * you should instead create a separate thread that does a blocking poll
115 * and set a Win32 event object. The event can then be passed to
116 * qemu_add_wait_object.
117 *
118 * Polling callbacks really have nothing Windows specific in them, but
119 * as they are a hack and are currently not necessary under POSIX systems,
120 * they are only available when QEMU is running under Windows.
121 *
122 * @func: The function that does the polling, and returns 1 to force
123 * immediate completion of main_loop_wait.
124 * @opaque: A pointer-size value that is passed to @func.
125 */
126 int qemu_add_polling_cb(PollingFunc *func, void *opaque);
127
128 /**
129 * qemu_del_polling_cb: Unregister a Windows-specific polling callback
130 *
131 * This function removes a callback that was registered with
132 * qemu_add_polling_cb.
133 *
134 * @func: The function that was passed to qemu_add_polling_cb.
135 * @opaque: A pointer-size value that was passed to qemu_add_polling_cb.
136 */
137 void qemu_del_polling_cb(PollingFunc *func, void *opaque);
138
139 /* Wait objects handling */
140 typedef void WaitObjectFunc(void *opaque);
141
142 /**
143 * qemu_add_wait_object: Register a callback for a Windows handle
144 *
145 * Under Windows, the iohandler mechanism can only be used with sockets.
146 * QEMU must use the WaitForMultipleObjects API to wait on other handles.
147 * This function registers a #HANDLE with QEMU, so that it will be included
148 * in the main loop's calls to WaitForMultipleObjects. When the handle
149 * is in a signaled state, QEMU will call @func.
150 *
151 * @handle: The Windows handle to be observed.
152 * @func: A function to be called when @handle is in a signaled state.
153 * @opaque: A pointer-size value that is passed to @func.
154 */
155 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque);
156
157 /**
158 * qemu_del_wait_object: Unregister a callback for a Windows handle
159 *
160 * This function removes a callback that was registered with
161 * qemu_add_wait_object.
162 *
163 * @func: The function that was passed to qemu_add_wait_object.
164 * @opaque: A pointer-size value that was passed to qemu_add_wait_object.
165 */
166 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque);
167 #endif
168
169 /* async I/O support */
170
171 typedef void IOReadHandler(void *opaque, const uint8_t *buf, int size);
172 typedef int IOCanReadHandler(void *opaque);
173
174 /**
175 * qemu_set_fd_handler2: Register a file descriptor with the main loop
176 *
177 * This function tells the main loop to wake up whenever one of the
178 * following conditions is true:
179 *
180 * 1) if @fd_write is not %NULL, when the file descriptor is writable;
181 *
182 * 2) if @fd_read is not %NULL, when the file descriptor is readable.
183 *
184 * @fd_read_poll can be used to disable the @fd_read callback temporarily.
185 * This is useful to avoid calling qemu_set_fd_handler2 every time the
186 * client becomes interested in reading (or dually, stops being interested).
187 * A typical example is when @fd is a listening socket and you want to bound
188 * the number of active clients. Remember to call qemu_notify_event whenever
189 * the condition may change from %false to %true.
190 *
191 * The callbacks that are set up by qemu_set_fd_handler2 are level-triggered.
192 * If @fd_read does not read from @fd, or @fd_write does not write to @fd
193 * until its buffers are full, they will be called again on the next
194 * iteration.
195 *
196 * @fd: The file descriptor to be observed. Under Windows it must be
197 * a #SOCKET.
198 *
199 * @fd_read_poll: A function that returns 1 if the @fd_read callback
200 * should be fired. If the function returns 0, the main loop will not
201 * end its iteration even if @fd becomes readable.
202 *
203 * @fd_read: A level-triggered callback that is fired if @fd is readable
204 * at the beginning of a main loop iteration, or if it becomes readable
205 * during one.
206 *
207 * @fd_write: A level-triggered callback that is fired when @fd is writable
208 * at the beginning of a main loop iteration, or if it becomes writable
209 * during one.
210 *
211 * @opaque: A pointer-sized value that is passed to @fd_read_poll,
212 * @fd_read and @fd_write.
213 */
214 int qemu_set_fd_handler2(int fd,
215 IOCanReadHandler *fd_read_poll,
216 IOHandler *fd_read,
217 IOHandler *fd_write,
218 void *opaque);
219
220 /**
221 * qemu_set_fd_handler: Register a file descriptor with the main loop
222 *
223 * This function tells the main loop to wake up whenever one of the
224 * following conditions is true:
225 *
226 * 1) if @fd_write is not %NULL, when the file descriptor is writable;
227 *
228 * 2) if @fd_read is not %NULL, when the file descriptor is readable.
229 *
230 * The callbacks that are set up by qemu_set_fd_handler are level-triggered.
231 * If @fd_read does not read from @fd, or @fd_write does not write to @fd
232 * until its buffers are full, they will be called again on the next
233 * iteration.
234 *
235 * @fd: The file descriptor to be observed. Under Windows it must be
236 * a #SOCKET.
237 *
238 * @fd_read: A level-triggered callback that is fired if @fd is readable
239 * at the beginning of a main loop iteration, or if it becomes readable
240 * during one.
241 *
242 * @fd_write: A level-triggered callback that is fired when @fd is writable
243 * at the beginning of a main loop iteration, or if it becomes writable
244 * during one.
245 *
246 * @opaque: A pointer-sized value that is passed to @fd_read and @fd_write.
247 */
248 int qemu_set_fd_handler(int fd,
249 IOHandler *fd_read,
250 IOHandler *fd_write,
251 void *opaque);
252
253 #ifdef CONFIG_POSIX
254 /**
255 * qemu_add_child_watch: Register a child process for reaping.
256 *
257 * Under POSIX systems, a parent process must read the exit status of
258 * its child processes using waitpid, or the operating system will not
259 * free some of the resources attached to that process.
260 *
261 * This function directs the QEMU main loop to observe a child process
262 * and call waitpid as soon as it exits; the watch is then removed
263 * automatically. It is useful whenever QEMU forks a child process
264 * but will find out about its termination by other means such as a
265 * "broken pipe".
266 *
267 * @pid: The pid that QEMU should observe.
268 */
269 int qemu_add_child_watch(pid_t pid);
270 #endif
271
272 /**
273 * qemu_mutex_lock_iothread: Lock the main loop mutex.
274 *
275 * This function locks the main loop mutex. The mutex is taken by
276 * qemu_init_main_loop and always taken except while waiting on
277 * external events (such as with select). The mutex should be taken
278 * by threads other than the main loop thread when calling
279 * qemu_bh_new(), qemu_set_fd_handler() and basically all other
280 * functions documented in this file.
281 *
282 * NOTE: tools currently are single-threaded and qemu_mutex_lock_iothread
283 * is a no-op there.
284 */
285 void qemu_mutex_lock_iothread(void);
286
287 /**
288 * qemu_mutex_unlock_iothread: Unlock the main loop mutex.
289 *
290 * This function unlocks the main loop mutex. The mutex is taken by
291 * qemu_init_main_loop and always taken except while waiting on
292 * external events (such as with select). The mutex should be unlocked
293 * as soon as possible by threads other than the main loop thread,
294 * because it prevents the main loop from processing callbacks,
295 * including timers and bottom halves.
296 *
297 * NOTE: tools currently are single-threaded and qemu_mutex_unlock_iothread
298 * is a no-op there.
299 */
300 void qemu_mutex_unlock_iothread(void);
301
302 /* internal interfaces */
303
304 void qemu_fd_register(int fd);
305 void qemu_iohandler_fill(GArray *pollfds);
306 void qemu_iohandler_poll(GArray *pollfds, int rc);
307
308 QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque);
309 void qemu_bh_schedule_idle(QEMUBH *bh);
310
311 #endif