This adds a -daemonize option. This option is mostly useful for
front-ends as it provides a deterministic way to connect to QEMU's
various devices. For instance, if you wanted to execute:
qemu -hda ~/win2k.img -monitor telnet:localhost:1024,server &
telnet localhost:1024
Occasionally, you will get a connection refused as there is a race
condition. However, with this option, you can write:
qemu -hda ~/win2k.img -monitor telnet:localhost:1024,server -daemonize
telnet localhost:1024
And it should always work. This is because the daemonize code doesn't
detach until after all of the character devices are initialized.
Regards,
Anthony Liguori
diff -r 953722fbdf7e qemu-doc.texi
--- a/qemu-doc.texi Sat Dec 16 11:50:12 2006 -0600
+++ b/qemu-doc.texi Sat Dec 16 11:50:23 2006 -0600
@@ -308,6 +308,12 @@ Start in full screen.
@item -pidfile file
Store the QEMU process PID in @var{file}. It is useful if you launch QEMU
from a script.
+
[EMAIL PROTECTED] -daemonize
+Daemonize the QEMU process after initialization. QEMU will not detach from
+standard IO until it is ready to receive connections on any of its devices.
+This option is a useful way for external programs to launch QEMU without having
+to cope with initialization race conditions.
@item -win2k-hack
Use it when installing Windows 2000 to avoid a disk full bug. After
diff -r 953722fbdf7e vl.c
--- a/vl.c Sat Dec 16 11:50:12 2006 -0600
+++ b/vl.c Sat Dec 16 11:50:15 2006 -0600
@@ -163,6 +163,7 @@ int acpi_enabled = 1;
int acpi_enabled = 1;
int fd_bootchk = 1;
int no_reboot = 0;
+int daemonize = 0;
/***********************************************************/
/* x86 ISA bus support */
@@ -6018,6 +6019,9 @@ void help(void)
"-no-reboot exit instead of rebooting\n"
"-loadvm file start right away with a saved state (loadvm in monitor)\n"
"-vnc display start a VNC server on display\n"
+#ifndef _WIN32
+ "-daemonize daemonize QEMU after initializing\n"
+#endif
"\n"
"During emulation, the following keys are useful:\n"
"ctrl-alt-f toggle full screen\n"
@@ -6098,6 +6102,7 @@ enum {
QEMU_OPTION_vnc,
QEMU_OPTION_no_acpi,
QEMU_OPTION_no_reboot,
+ QEMU_OPTION_daemonize,
};
typedef struct QEMUOption {
@@ -6178,6 +6183,7 @@ const QEMUOption qemu_options[] = {
{ "cirrusvga", 0, QEMU_OPTION_cirrusvga },
{ "no-acpi", 0, QEMU_OPTION_no_acpi },
{ "no-reboot", 0, QEMU_OPTION_no_reboot },
+ { "daemonize", 0, QEMU_OPTION_daemonize },
{ NULL },
};
@@ -6408,6 +6414,7 @@ int main(int argc, char **argv)
QEMUMachine *machine;
char usb_devices[MAX_USB_CMDLINE][128];
int usb_devices_index;
+ int fds[2];
LIST_INIT (&vm_change_state_head);
#ifndef _WIN32
@@ -6826,9 +6833,59 @@ int main(int argc, char **argv)
case QEMU_OPTION_no_reboot:
no_reboot = 1;
break;
+ case QEMU_OPTION_daemonize:
+ daemonize = 1;
}
}
}
+
+#ifndef _WIN32
+ if (daemonize && !nographic && vnc_display == NULL) {
+ fprintf(stderr, "Can only daemonize if using -nographic or -vnc\n");
+ daemonize = 0;
+ }
+
+ if (daemonize) {
+ pid_t pid;
+
+ if (pipe(fds) == -1)
+ exit(1);
+
+ pid = fork();
+ if (pid > 0) {
+ uint8_t status;
+ ssize_t len;
+
+ close(fds[1]);
+
+ again:
+ len = read(fds[0], &status, 1);
+ if (len == -1 && (errno == EINTR))
+ goto again;
+
+ if (len != 1 || status != 0)
+ exit(1);
+ else
+ exit(0);
+ } else if (pid < 0)
+ exit(1);
+
+ setsid();
+
+ pid = fork();
+ if (pid > 0)
+ exit(0);
+ else if (pid < 0)
+ exit(1);
+
+ umask(027);
+ chdir("/");
+
+ signal(SIGTSTP, SIG_IGN);
+ signal(SIGTTOU, SIG_IGN);
+ signal(SIGTTIN, SIG_IGN);
+ }
+#endif
#ifdef USE_KQEMU
if (smp_cpus > 1)
@@ -7028,6 +7085,30 @@ int main(int argc, char **argv)
}
}
+ if (daemonize) {
+ uint8_t status = 0;
+ ssize_t len;
+ int fd;
+
+ again1:
+ len = write(fds[1], &status, 1);
+ if (len == -1 && (errno == EINTR))
+ goto again1;
+
+ if (len != 1)
+ exit(1);
+
+ fd = open("/dev/null", O_RDWR);
+ if (fd == -1)
+ exit(1);
+
+ dup2(fd, 0);
+ dup2(fd, 1);
+ dup2(fd, 2);
+
+ close(fd);
+ }
+
main_loop();
quit_timers();
return 0;
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