1. qemu migration入口函数
主要做以下工作：
1）分析传入参数；
2) 创建管道和进程；
3）调用start_migration()开始迁移；
4）suspend qemu monitor;
+/* Migration monitor command */
+
+void do_migrate(int detach, const char *uri)
+{
+ MigrationState *s;
+ int fds[2];
+ const char *ptr;
+ char *command = NULL;
+ char **argv = NULL;
+ int i;
+
+ if (strstart(uri, "exec:", &ptr)) {
+ char *subcommand = urldecode(ptr);
+ if (subcommand == NULL) {
+ term_printf("Allocation error\n");
+ return;
+ }
+
+ command = strdup("/bin/sh");
+ argv = qemu_mallocz(sizeof(char *) * 4);
+ argv[0] = strdup("sh");
+ argv[1] = strdup("-c");
+ argv[2] = subcommand;
+ argv[3] = NULL;
+ } else if (strstart(uri, "ssh:", &ptr)) {
+ char *host, *end;
+ int qemu_argc, daemonize = 0, incoming = 0, argc, i;
+ char **qemu_argv;
+
+ if (ptr[0] != '/' && ptr[1] != '/') {
+ term_printf("Malformed ssh uri\n");
+ return;
+ }
+
+ qemu_get_launch_info(&qemu_argc, &qemu_argv, &daemonize, &incoming);
+
+ argc = 3 + qemu_argc;
+ if (!daemonize)
+ argc++;
+ if (!incoming)
+ argc++;
+
+ host = strdup(ptr + 2);
+ end = strchr(host, '/');
+ if (end) *end = 0;
+
+ command = strdup("ssh");
+ argv = qemu_mallocz(sizeof(char *) * (argc + 1));
+ argv[0] = strdup("ssh");
+ argv[1] = strdup("-XC");
+ argv[2] = host;
+
+ for (i = 0; i < qemu_argc; i++)
+ argv[3 + i] = strdup(qemu_argv[i]);
+
+ if (!daemonize)
+ argv[3 + i++] = strdup("-daemonize");
+ if (!incoming)
+ argv[3 + i++] = strdup("-incoming");
+ argv[3 + i] = NULL;
+ } else {
+ term_printf("Unknown migration protocol '%s'\n", uri);
+ return;
+ }
+
+ if (pipe(fds) == -1) {
+ term_printf("pipe()\n");
+ return;
+ }
+
+#if 0
+ term_printf("execlp('%s'", command);
+ for (i = 0; argv[i]; i++) {
+ term_printf(", '%s'", argv[i]);
+ }
+ term_printf(", NULL);\n");
+ return;
+#endif
+
+ s = qemu_mallocz(sizeof(MigrationState));
+ if (s == NULL) {
+ term_printf("Allocation error\n");
+ return;
+ }
+
+ s->fd = fds[1];
+ s->pid = fork();
+ if (s->pid == -1) {
+ term_printf("fork error\n");
+ return;
+ }
+ if (s->pid == 0) {
+ close(fds[1]);
+ dup2(fds[0], STDIN_FILENO);
+ execvp(command, argv);
+ exit(1);
+ } else
+ close(fds[0]);
+
+ s->detach = detach;
+ s->has_error = qemu_mallocz(sizeof(int));
+#if 1
+ qemu_free(command);
+ for (i = 0; argv[i]; i++)
+ qemu_free(argv[i]);
+ qemu_free(argv);
+#endif
+
+ if (start_migration(s) == -1)
+ term_printf("Could not start migration\n");
+ else if (!s->detach)
+ monitor_suspend();
+}
2.