[PATCH 0/3] ui/cocoa: Run qemu_init in the main thread

[PATCH 0/3] ui/cocoa: Run qemu_init in the main thread

[Akihiko Odaki]

This work is based on:
https://patchew.org/QEMU/20220317125534.38706-1-philippe.mathieu.daude@gmail.com/

Simplify the initialization dance by running qemu_init() in the main
thread before the Cocoa event loop starts. The secondary thread only
runs only qemu_main_loop() and qemu_cleanup().

This fixes a case where addRemovableDevicesMenuItems() calls
qmp_query_block() while expecting the main thread to still hold
the BQL.

Overriding the code after calling qemu_init() is done by dynamically
replacing a function pointer variable, qemu_main when initializing
ui/cocoa, which unifies the static implementation of main() for
builds with ui/cocoa and ones without ui/cocoa.

Akihiko Odaki (3):
  ui/cocoa: Run qemu_init in the main thread
  Revert "main-loop: Disable block backend global state assertion on
    Cocoa"
  meson: Allow to enable gtk and sdl while cocoa is enabled

 docs/devel/fuzzing.rst   |   4 +-
 include/qemu-main.h      |   3 +-
 include/qemu/main-loop.h |  13 ---
 include/sysemu/sysemu.h  |   2 +-
 meson.build              |  10 +--
 softmmu/main.c           |  14 +--
 softmmu/vl.c             |   2 +-
 tests/qtest/fuzz/fuzz.c  |   2 +-
 ui/cocoa.m               | 185 ++++++++++++---------------------------
 9 files changed, 71 insertions(+), 164 deletions(-)

-- 
2.32.1 (Apple Git-133)

[PATCH 1/3] ui/cocoa: Run qemu_init in the main thread

[Akihiko Odaki]

This work is based on:
https://patchew.org/QEMU/20220317125534.38706-1-philippe.mathieu.daude@gmail.com/

Simplify the initialization dance by running qemu_init() in the main
thread before the Cocoa event loop starts. The secondary thread only
runs only qemu_main_loop() and qemu_cleanup().

This fixes a case where addRemovableDevicesMenuItems() calls
qmp_query_block() while expecting the main thread to still hold
the BQL.

Overriding the code after calling qemu_init() is done by dynamically
replacing a function pointer variable, qemu_main when initializing
ui/cocoa, which unifies the static implementation of main() for
builds with ui/cocoa and ones without ui/cocoa.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
---
 docs/devel/fuzzing.rst  |   4 +-
 include/qemu-main.h     |   3 +-
 include/sysemu/sysemu.h |   2 +-
 softmmu/main.c          |  14 +--
 softmmu/vl.c            |   2 +-
 tests/qtest/fuzz/fuzz.c |   2 +-
 ui/cocoa.m              | 185 ++++++++++++----------------------------
 7 files changed, 69 insertions(+), 143 deletions(-)

diff --git a/docs/devel/fuzzing.rst b/docs/devel/fuzzing.rst
index 784ecb99e66..715330c8561 100644
--- a/docs/devel/fuzzing.rst
+++ b/docs/devel/fuzzing.rst
@@ -287,8 +287,8 @@ select the fuzz target. Then, the qtest client is initialized. If the target
 requires qos, qgraph is set up and the QOM/LIBQOS modules are initialized.
 Then the QGraph is walked and the QEMU cmd_line is determined and saved.
 
-After this, the ``vl.c:qemu_main`` is called to set up the guest. There are
-target-specific hooks that can be called before and after qemu_main, for
+After this, the ``vl.c:main`` is called to set up the guest. There are
+target-specific hooks that can be called before and after main, for
 additional setup(e.g. PCI setup, or VM snapshotting).
 
 ``LLVMFuzzerTestOneInput``: Uses qtest/qos functions to act based on the fuzz
diff --git a/include/qemu-main.h b/include/qemu-main.h
index 6a3e90d0ad5..6889375e7c2 100644
--- a/include/qemu-main.h
+++ b/include/qemu-main.h
@@ -5,6 +5,7 @@
 #ifndef QEMU_MAIN_H
 #define QEMU_MAIN_H
 
-int qemu_main(int argc, char **argv, char **envp);
+void qemu_default_main(void);
+extern void (*qemu_main)(void);
 
 #endif /* QEMU_MAIN_H */
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 812f66a31a9..254c1eabf57 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -102,7 +102,7 @@ void qemu_boot_set(const char *boot_order, Error **errp);
 
 bool defaults_enabled(void);
 
-void qemu_init(int argc, char **argv, char **envp);
+void qemu_init(int argc, char **argv);
 void qemu_main_loop(void);
 void qemu_cleanup(void);
 
diff --git a/softmmu/main.c b/softmmu/main.c
index c00432ff098..41a091f2c72 100644
--- a/softmmu/main.c
+++ b/softmmu/main.c
@@ -30,18 +30,18 @@
 #include <SDL.h>
 #endif
 
-int qemu_main(int argc, char **argv, char **envp)
+void qemu_default_main(void)
 {
-    qemu_init(argc, argv, envp);
     qemu_main_loop();
     qemu_cleanup();
-
-    return 0;
 }
 
-#ifndef CONFIG_COCOA
+void (*qemu_main)(void) = qemu_default_main;
+
 int main(int argc, char **argv)
 {
-    return qemu_main(argc, argv, NULL);
+    qemu_init(argc, argv);
+    qemu_main();
+
+    return 0;
 }
-#endif
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 3f264d4b093..e8c73d0bb40 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2589,7 +2589,7 @@ void qmp_x_exit_preconfig(Error **errp)
     }
 }
 
-void qemu_init(int argc, char **argv, char **envp)
+void qemu_init(int argc, char **argv)
 {
     QemuOpts *opts;
     QemuOpts *icount_opts = NULL, *accel_opts = NULL;
diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
index 2062b40d82b..0bde925bf83 100644
--- a/tests/qtest/fuzz/fuzz.c
+++ b/tests/qtest/fuzz/fuzz.c
@@ -221,7 +221,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
         g_free(pretty_cmd_line);
     }
 
-    qemu_init(result.we_wordc, result.we_wordv, NULL);
+    qemu_init(result.we_wordc, result.we_wordv);
 
     /* re-enable the rcu atfork, which was previously disabled in qemu_init */
     rcu_enable_atfork();
diff --git a/ui/cocoa.m b/ui/cocoa.m
index 6a4dccff7f0..55413594d14 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -100,15 +100,11 @@ static void cocoa_switch(DisplayChangeListener *dcl,
 static int left_command_key_enabled = 1;
 static bool swap_opt_cmd;
 
-static int gArgc;
-static char **gArgv;
+static QemuThread qemu_main_thread;
+static bool qemu_main_terminating;
 static bool stretch_video;
 static NSTextField *pauseLabel;
 
-static QemuSemaphore display_init_sem;
-static QemuSemaphore app_started_sem;
-static bool allow_events;
-
 static NSInteger cbchangecount = -1;
 static QemuClipboardInfo *cbinfo;
 static QemuEvent cbevent;
@@ -581,18 +577,6 @@ - (void) updateUIInfoLocked
 
 - (void) updateUIInfo
 {
-    if (!allow_events) {
-        /*
-         * Don't try to tell QEMU about UI information in the application
-         * startup phase -- we haven't yet registered dcl with the QEMU UI
-         * layer, and also trying to take the iothread lock would deadlock.
-         * When cocoa_display_init() does register the dcl, the UI layer
-         * will call cocoa_switch(), which will call updateUIInfo, so
-         * we don't lose any information here.
-         */
-        return;
-    }
-
     with_iothread_lock(^{
         [self updateUIInfoLocked];
     });
@@ -778,16 +762,6 @@ - (void) handleMonitorInput:(NSEvent *)event
 
 - (bool) handleEvent:(NSEvent *)event
 {
-    if(!allow_events) {
-        /*
-         * Just let OSX have all events that arrive before
-         * applicationDidFinishLaunching.
-         * This avoids a deadlock on the iothread lock, which cocoa_display_init()
-         * will not drop until after the app_started_sem is posted. (In theory
-         * there should not be any such events, but OSX Catalina now emits some.)
-         */
-        return false;
-    }
     return bool_with_iothread_lock(^{
         return [self handleEventLocked:event];
     });
@@ -1279,29 +1253,18 @@ - (void) dealloc
     [super dealloc];
 }
 
-- (void)applicationDidFinishLaunching: (NSNotification *) note
-{
-    COCOA_DEBUG("QemuCocoaAppController: applicationDidFinishLaunching\n");
-    allow_events = true;
-    /* Tell cocoa_display_init to proceed */
-    qemu_sem_post(&app_started_sem);
-}
-
 - (void)applicationWillTerminate:(NSNotification *)aNotification
 {
     COCOA_DEBUG("QemuCocoaAppController: applicationWillTerminate\n");
 
     with_iothread_lock(^{
-        shutdown_action = SHUTDOWN_ACTION_POWEROFF;
-        qemu_system_shutdown_request(SHUTDOWN_CAUSE_HOST_UI);
+        if (!qemu_main_terminating) {
+            shutdown_action = SHUTDOWN_ACTION_POWEROFF;
+            qemu_system_shutdown_request(SHUTDOWN_CAUSE_HOST_UI);
+        }
     });
 
-    /*
-     * Sleep here, because returning will cause OSX to kill us
-     * immediately; the QEMU main loop will handle the shutdown
-     * request and terminate the process.
-     */
-    [NSThread sleepForTimeInterval:INFINITY];
+    qemu_thread_join(&qemu_main_thread);
 }
 
 - (BOOL)applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)theApplication
@@ -1313,7 +1276,7 @@ - (NSApplicationTerminateReply)applicationShouldTerminate:
                                                          (NSApplication *)sender
 {
     COCOA_DEBUG("QemuCocoaAppController: applicationShouldTerminate\n");
-    return [self verifyQuit];
+    return qatomic_read(&qemu_main_terminating) || [self verifyQuit];
 }
 
 - (void)windowDidChangeScreen:(NSNotification *)notification
@@ -1915,92 +1878,35 @@ static void cocoa_clipboard_request(QemuClipboardInfo *info,
 /*
  * The startup process for the OSX/Cocoa UI is complicated, because
  * OSX insists that the UI runs on the initial main thread, and so we
- * need to start a second thread which runs the vl.c qemu_main():
- *
- * Initial thread:                    2nd thread:
- * in main():
- *  create qemu-main thread
- *  wait on display_init semaphore
- *                                    call qemu_main()
- *                                    ...
- *                                    in cocoa_display_init():
- *                                     post the display_init semaphore
- *                                     wait on app_started semaphore
- *  create application, menus, etc
- *  enter OSX run loop
- * in applicationDidFinishLaunching:
- *  post app_started semaphore
- *                                     tell main thread to fullscreen if needed
- *                                    [...]
- *                                    run qemu main-loop
- *
- * We do this in two stages so that we don't do the creation of the
- * GUI application menus and so on for command line options like --help
- * where we want to just print text to stdout and exit immediately.
+ * need to start a second thread which runs the qemu_default_main().
  */
 
 static void *call_qemu_main(void *opaque)
 {
-    int status;
-
-    COCOA_DEBUG("Second thread: calling qemu_main()\n");
-    status = qemu_main(gArgc, gArgv, *_NSGetEnviron());
-    COCOA_DEBUG("Second thread: qemu_main() returned, exiting\n");
+    COCOA_DEBUG("Second thread: calling qemu_default_main()\n");
+    qemu_mutex_lock_iothread();
+    qemu_default_main();
+    qatomic_set(&qemu_main_terminating, true);
+    qemu_mutex_unlock_iothread();
+    COCOA_DEBUG("Second thread: qemu_default_main() returned, exiting\n");
     [cbowner release];
-    exit(status);
-}
-
-int main (int argc, char **argv) {
-    QemuThread thread;
-
-    COCOA_DEBUG("Entered main()\n");
-    gArgc = argc;
-    gArgv = argv;
+    [NSApp terminate:nil];
 
-    qemu_sem_init(&display_init_sem, 0);
-    qemu_sem_init(&app_started_sem, 0);
-
-    qemu_thread_create(&thread, "qemu_main", call_qemu_main,
-                       NULL, QEMU_THREAD_DETACHED);
-
-    COCOA_DEBUG("Main thread: waiting for display_init_sem\n");
-    qemu_sem_wait(&display_init_sem);
-    COCOA_DEBUG("Main thread: initializing app\n");
-
-    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
-
-    // Pull this console process up to being a fully-fledged graphical
-    // app with a menubar and Dock icon
-    ProcessSerialNumber psn = { 0, kCurrentProcess };
-    TransformProcessType(&psn, kProcessTransformToForegroundApplication);
-
-    [QemuApplication sharedApplication];
-
-    create_initial_menus();
+    return NULL;
+}
 
-    /*
-     * Create the menu entries which depend on QEMU state (for consoles
-     * and removeable devices). These make calls back into QEMU functions,
-     * which is OK because at this point we know that the second thread
-     * holds the iothread lock and is synchronously waiting for us to
-     * finish.
-     */
-    add_console_menu_entries();
-    addRemovableDevicesMenuItems();
+static void cocoa_main()
+{
+    COCOA_DEBUG("Entered %s()\n", __func__);
 
-    // Create an Application controller
-    QemuCocoaAppController *appController = [[QemuCocoaAppController alloc] init];
-    [NSApp setDelegate:appController];
+    qemu_mutex_unlock_iothread();
+    qemu_thread_create(&qemu_main_thread, "qemu_main", call_qemu_main,
+                       NULL, QEMU_THREAD_JOINABLE);
 
     // Start the main event loop
     COCOA_DEBUG("Main thread: entering OSX run loop\n");
     [NSApp run];
     COCOA_DEBUG("Main thread: left OSX run loop, exiting\n");
-
-    [appController release];
-    [pool release];
-
-    return 0;
 }
 
 
@@ -2079,25 +1985,42 @@ static void cocoa_refresh(DisplayChangeListener *dcl)
 
 static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
 {
+    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
+
     COCOA_DEBUG("qemu_cocoa: cocoa_display_init\n");
 
-    /* Tell main thread to go ahead and create the app and enter the run loop */
-    qemu_sem_post(&display_init_sem);
-    qemu_sem_wait(&app_started_sem);
-    COCOA_DEBUG("cocoa_display_init: app start completed\n");
+    qemu_main = cocoa_main;
+
+    // Pull this console process up to being a fully-fledged graphical
+    // app with a menubar and Dock icon
+    ProcessSerialNumber psn = { 0, kCurrentProcess };
+    TransformProcessType(&psn, kProcessTransformToForegroundApplication);
+
+    [QemuApplication sharedApplication];
+
+    create_initial_menus();
+
+    /*
+     * Create the menu entries which depend on QEMU state (for consoles
+     * and removeable devices). These make calls back into QEMU functions,
+     * which is OK because at this point we know that the second thread
+     * holds the iothread lock and is synchronously waiting for us to
+     * finish.
+     */
+    add_console_menu_entries();
+    addRemovableDevicesMenuItems();
+
+    // Create an Application controller
+    QemuCocoaAppController *controller = [[QemuCocoaAppController alloc] init];
+    [NSApp setDelegate:controller];
 
-    QemuCocoaAppController *controller = (QemuCocoaAppController *)[[NSApplication sharedApplication] delegate];
     /* if fullscreen mode is to be used */
     if (opts->has_full_screen && opts->full_screen) {
-        dispatch_async(dispatch_get_main_queue(), ^{
-            [NSApp activateIgnoringOtherApps: YES];
-            [controller toggleFullScreen: nil];
-        });
+        [NSApp activateIgnoringOtherApps: YES];
+        [controller toggleFullScreen: nil];
     }
     if (opts->u.cocoa.has_full_grab && opts->u.cocoa.full_grab) {
-        dispatch_async(dispatch_get_main_queue(), ^{
-            [controller setFullGrab: nil];
-        });
+        [controller setFullGrab: nil];
     }
 
     if (opts->has_show_cursor && opts->show_cursor) {
@@ -2117,6 +2040,8 @@ static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
     qemu_event_init(&cbevent, false);
     cbowner = [[QemuCocoaPasteboardTypeOwner alloc] init];
     qemu_clipboard_peer_register(&cbpeer);
+
+    [pool release];
 }
 
 static QemuDisplay qemu_display_cocoa = {
-- 
2.32.1 (Apple Git-133)

[PATCH 2/3] Revert "main-loop: Disable block backend global state assertion on Cocoa"

[Akihiko Odaki]

This reverts commit 47281859f66bdab1974fb122cab2cbb4a1c9af7f.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
---
 include/qemu/main-loop.h | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
index 5518845299d..0aa36a4f17e 100644
--- a/include/qemu/main-loop.h
+++ b/include/qemu/main-loop.h
@@ -280,23 +280,10 @@ bool qemu_mutex_iothread_locked(void);
 bool qemu_in_main_thread(void);
 
 /* Mark and check that the function is part of the global state API. */
-#ifdef CONFIG_COCOA
-/*
- * When using the Cocoa UI, addRemovableDevicesMenuItems() is called from
- * a thread different from the QEMU main thread and can not take the BQL,
- * triggering this assertions in the block layer (commit 0439c5a462).
- * As the Cocoa fix is not trivial, disable this assertion for the v7.0.0
- * release (when using Cocoa); we will restore it immediately after the
- * release.
- * This issue is tracked as https://gitlab.com/qemu-project/qemu/-/issues/926
- */
-#define GLOBAL_STATE_CODE()
-#else
 #define GLOBAL_STATE_CODE()                                         \
     do {                                                            \
         assert(qemu_in_main_thread());                              \
     } while (0)
-#endif /* CONFIG_COCOA */
 
 /* Mark and check that the function is part of the I/O API. */
 #define IO_CODE()                                                   \
-- 
2.32.1 (Apple Git-133)

[PATCH 3/3] meson: Allow to enable gtk and sdl while cocoa is enabled

[Akihiko Odaki]

As ui/cocoa does no longer override main(), ui/gtk and ui/sdl
can be enabled even ui/cocoa is enabled.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
---
 meson.build | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/meson.build b/meson.build
index 6e1c3eb2bc5..4714a0d5cf8 100644
--- a/meson.build
+++ b/meson.build
@@ -587,12 +587,6 @@ if get_option('attr').allowed()
 endif
 
 cocoa = dependency('appleframeworks', modules: 'Cocoa', required: get_option('cocoa'))
-if cocoa.found() and get_option('sdl').enabled()
-  error('Cocoa and SDL cannot be enabled at the same time')
-endif
-if cocoa.found() and get_option('gtk').enabled()
-  error('Cocoa and GTK+ cannot be enabled at the same time')
-endif
 
 vmnet = dependency('appleframeworks', modules: 'vmnet', required: get_option('vmnet'))
 if vmnet.found() and not cc.has_header_symbol('vmnet/vmnet.h',
@@ -919,7 +913,7 @@ if not get_option('brlapi').auto() or have_system
 endif
 
 sdl = not_found
-if not get_option('sdl').auto() or (have_system and not cocoa.found())
+if not get_option('sdl').auto() or have_system
   sdl = dependency('sdl2', required: get_option('sdl'), kwargs: static_kwargs)
   sdl_image = not_found
 endif
@@ -1185,7 +1179,7 @@ endif
 gtk = not_found
 gtkx11 = not_found
 vte = not_found
-if not get_option('gtk').auto() or (have_system and not cocoa.found())
+if not get_option('gtk').auto() or have_system
   gtk = dependency('gtk+-3.0', version: '>=3.22.0',
                    method: 'pkg-config',
                    required: get_option('gtk'),
-- 
2.32.1 (Apple Git-133)

Re: [PATCH 2/3] Revert "main-loop: Disable block backend global state assertion on Cocoa"

[Emanuele Giuseppe Esposito]

Am 06/07/2022 um 04:13 schrieb Akihiko Odaki:
> This reverts commit 47281859f66bdab1974fb122cab2cbb4a1c9af7f.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
> ---
>  include/qemu/main-loop.h | 13 -------------
>  1 file changed, 13 deletions(-)

Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>

Re: [PATCH 1/3] ui/cocoa: Run qemu_init in the main thread

[Philippe Mathieu-Daudé via]

Hi Akihiko,

On 6/7/22 04:13, Akihiko Odaki wrote:
> This work is based on:
> https://patchew.org/QEMU/20220317125534.38706-1-philippe.mathieu.daude@gmail.com/
> 
> Simplify the initialization dance by running qemu_init() in the main
> thread before the Cocoa event loop starts. The secondary thread only
> runs only qemu_main_loop() and qemu_cleanup().
> 
> This fixes a case where addRemovableDevicesMenuItems() calls
> qmp_query_block() while expecting the main thread to still hold
> the BQL.
> 
> Overriding the code after calling qemu_init() is done by dynamically
> replacing a function pointer variable, qemu_main when initializing
> ui/cocoa, which unifies the static implementation of main() for
> builds with ui/cocoa and ones without ui/cocoa.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
> ---
>   docs/devel/fuzzing.rst  |   4 +-
>   include/qemu-main.h     |   3 +-
>   include/sysemu/sysemu.h |   2 +-
>   softmmu/main.c          |  14 +--
>   softmmu/vl.c            |   2 +-
>   tests/qtest/fuzz/fuzz.c |   2 +-
>   ui/cocoa.m              | 185 ++++++++++++----------------------------
>   7 files changed, 69 insertions(+), 143 deletions(-)
> 
> diff --git a/docs/devel/fuzzing.rst b/docs/devel/fuzzing.rst
> index 784ecb99e66..715330c8561 100644
> --- a/docs/devel/fuzzing.rst
> +++ b/docs/devel/fuzzing.rst
> @@ -287,8 +287,8 @@ select the fuzz target. Then, the qtest client is initialized. If the target
>   requires qos, qgraph is set up and the QOM/LIBQOS modules are initialized.
>   Then the QGraph is walked and the QEMU cmd_line is determined and saved.
>   
> -After this, the ``vl.c:qemu_main`` is called to set up the guest. There are
> -target-specific hooks that can be called before and after qemu_main, for
> +After this, the ``vl.c:main`` is called to set up the guest. There are
> +target-specific hooks that can be called before and after main, for
>   additional setup(e.g. PCI setup, or VM snapshotting).
>   
>   ``LLVMFuzzerTestOneInput``: Uses qtest/qos functions to act based on the fuzz
> diff --git a/include/qemu-main.h b/include/qemu-main.h
> index 6a3e90d0ad5..6889375e7c2 100644
> --- a/include/qemu-main.h
> +++ b/include/qemu-main.h
> @@ -5,6 +5,7 @@
>   #ifndef QEMU_MAIN_H
>   #define QEMU_MAIN_H
>   
> -int qemu_main(int argc, char **argv, char **envp);
> +void qemu_default_main(void);
> +extern void (*qemu_main)(void);
>   
>   #endif /* QEMU_MAIN_H */
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index 812f66a31a9..254c1eabf57 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -102,7 +102,7 @@ void qemu_boot_set(const char *boot_order, Error **errp);
>   
>   bool defaults_enabled(void);
>   
> -void qemu_init(int argc, char **argv, char **envp);
> +void qemu_init(int argc, char **argv);
>   void qemu_main_loop(void);
>   void qemu_cleanup(void);
>   
> diff --git a/softmmu/main.c b/softmmu/main.c
> index c00432ff098..41a091f2c72 100644
> --- a/softmmu/main.c
> +++ b/softmmu/main.c
> @@ -30,18 +30,18 @@
>   #include <SDL.h>
>   #endif
>   
> -int qemu_main(int argc, char **argv, char **envp)
> +void qemu_default_main(void)
>   {
> -    qemu_init(argc, argv, envp);
>       qemu_main_loop();
>       qemu_cleanup();
> -
> -    return 0;
>   }
>   
> -#ifndef CONFIG_COCOA
> +void (*qemu_main)(void) = qemu_default_main;
> +
>   int main(int argc, char **argv)
>   {
> -    return qemu_main(argc, argv, NULL);
> +    qemu_init(argc, argv);
> +    qemu_main();
> +
> +    return 0;
>   }
> -#endif
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index 3f264d4b093..e8c73d0bb40 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -2589,7 +2589,7 @@ void qmp_x_exit_preconfig(Error **errp)
>       }
>   }
>   
> -void qemu_init(int argc, char **argv, char **envp)
> +void qemu_init(int argc, char **argv)
>   {
>       QemuOpts *opts;
>       QemuOpts *icount_opts = NULL, *accel_opts = NULL;
> diff --git a/tests/qtest/fuzz/fuzz.c b/tests/qtest/fuzz/fuzz.c
> index 2062b40d82b..0bde925bf83 100644
> --- a/tests/qtest/fuzz/fuzz.c
> +++ b/tests/qtest/fuzz/fuzz.c
> @@ -221,7 +221,7 @@ int LLVMFuzzerInitialize(int *argc, char ***argv, char ***envp)
>           g_free(pretty_cmd_line);
>       }
>   
> -    qemu_init(result.we_wordc, result.we_wordv, NULL);
> +    qemu_init(result.we_wordc, result.we_wordv);
>   
>       /* re-enable the rcu atfork, which was previously disabled in qemu_init */
>       rcu_enable_atfork();
> diff --git a/ui/cocoa.m b/ui/cocoa.m
> index 6a4dccff7f0..55413594d14 100644
> --- a/ui/cocoa.m
> +++ b/ui/cocoa.m
> @@ -100,15 +100,11 @@ static void cocoa_switch(DisplayChangeListener *dcl,
>   static int left_command_key_enabled = 1;
>   static bool swap_opt_cmd;
>   
> -static int gArgc;
> -static char **gArgv;
> +static QemuThread qemu_main_thread;
> +static bool qemu_main_terminating;
>   static bool stretch_video;
>   static NSTextField *pauseLabel;
>   
> -static QemuSemaphore display_init_sem;
> -static QemuSemaphore app_started_sem;
> -static bool allow_events;
> -
>   static NSInteger cbchangecount = -1;
>   static QemuClipboardInfo *cbinfo;
>   static QemuEvent cbevent;
> @@ -581,18 +577,6 @@ - (void) updateUIInfoLocked
>   
>   - (void) updateUIInfo
>   {
> -    if (!allow_events) {
> -        /*
> -         * Don't try to tell QEMU about UI information in the application
> -         * startup phase -- we haven't yet registered dcl with the QEMU UI
> -         * layer, and also trying to take the iothread lock would deadlock.
> -         * When cocoa_display_init() does register the dcl, the UI layer
> -         * will call cocoa_switch(), which will call updateUIInfo, so
> -         * we don't lose any information here.
> -         */
> -        return;
> -    }
> -
>       with_iothread_lock(^{
>           [self updateUIInfoLocked];
>       });
> @@ -778,16 +762,6 @@ - (void) handleMonitorInput:(NSEvent *)event
>   
>   - (bool) handleEvent:(NSEvent *)event
>   {
> -    if(!allow_events) {
> -        /*
> -         * Just let OSX have all events that arrive before
> -         * applicationDidFinishLaunching.
> -         * This avoids a deadlock on the iothread lock, which cocoa_display_init()
> -         * will not drop until after the app_started_sem is posted. (In theory
> -         * there should not be any such events, but OSX Catalina now emits some.)
> -         */
> -        return false;
> -    }
>       return bool_with_iothread_lock(^{
>           return [self handleEventLocked:event];
>       });
> @@ -1279,29 +1253,18 @@ - (void) dealloc
>       [super dealloc];
>   }
>   
> -- (void)applicationDidFinishLaunching: (NSNotification *) note
> -{
> -    COCOA_DEBUG("QemuCocoaAppController: applicationDidFinishLaunching\n");
> -    allow_events = true;
> -    /* Tell cocoa_display_init to proceed */
> -    qemu_sem_post(&app_started_sem);
> -}
> -
>   - (void)applicationWillTerminate:(NSNotification *)aNotification
>   {
>       COCOA_DEBUG("QemuCocoaAppController: applicationWillTerminate\n");
>   
>       with_iothread_lock(^{
> -        shutdown_action = SHUTDOWN_ACTION_POWEROFF;
> -        qemu_system_shutdown_request(SHUTDOWN_CAUSE_HOST_UI);
> +        if (!qemu_main_terminating) {
> +            shutdown_action = SHUTDOWN_ACTION_POWEROFF;
> +            qemu_system_shutdown_request(SHUTDOWN_CAUSE_HOST_UI);
> +        }
>       });
>   
> -    /*
> -     * Sleep here, because returning will cause OSX to kill us
> -     * immediately; the QEMU main loop will handle the shutdown
> -     * request and terminate the process.
> -     */
> -    [NSThread sleepForTimeInterval:INFINITY];
> +    qemu_thread_join(&qemu_main_thread);
>   }
>   
>   - (BOOL)applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)theApplication
> @@ -1313,7 +1276,7 @@ - (NSApplicationTerminateReply)applicationShouldTerminate:
>                                                            (NSApplication *)sender
>   {
>       COCOA_DEBUG("QemuCocoaAppController: applicationShouldTerminate\n");
> -    return [self verifyQuit];
> +    return qatomic_read(&qemu_main_terminating) || [self verifyQuit];
>   }
>   
>   - (void)windowDidChangeScreen:(NSNotification *)notification
> @@ -1915,92 +1878,35 @@ static void cocoa_clipboard_request(QemuClipboardInfo *info,
>   /*
>    * The startup process for the OSX/Cocoa UI is complicated, because
>    * OSX insists that the UI runs on the initial main thread, and so we
> - * need to start a second thread which runs the vl.c qemu_main():
> - *
> - * Initial thread:                    2nd thread:
> - * in main():
> - *  create qemu-main thread
> - *  wait on display_init semaphore
> - *                                    call qemu_main()
> - *                                    ...
> - *                                    in cocoa_display_init():
> - *                                     post the display_init semaphore
> - *                                     wait on app_started semaphore
> - *  create application, menus, etc
> - *  enter OSX run loop
> - * in applicationDidFinishLaunching:
> - *  post app_started semaphore
> - *                                     tell main thread to fullscreen if needed
> - *                                    [...]
> - *                                    run qemu main-loop
> - *
> - * We do this in two stages so that we don't do the creation of the
> - * GUI application menus and so on for command line options like --help
> - * where we want to just print text to stdout and exit immediately.
> + * need to start a second thread which runs the qemu_default_main().
>    */
>   
>   static void *call_qemu_main(void *opaque)
>   {
> -    int status;
> -
> -    COCOA_DEBUG("Second thread: calling qemu_main()\n");
> -    status = qemu_main(gArgc, gArgv, *_NSGetEnviron());
> -    COCOA_DEBUG("Second thread: qemu_main() returned, exiting\n");
> +    COCOA_DEBUG("Second thread: calling qemu_default_main()\n");
> +    qemu_mutex_lock_iothread();
> +    qemu_default_main();
> +    qatomic_set(&qemu_main_terminating, true);
> +    qemu_mutex_unlock_iothread();
> +    COCOA_DEBUG("Second thread: qemu_default_main() returned, exiting\n");
>       [cbowner release];
> -    exit(status);
> -}
> -
> -int main (int argc, char **argv) {
> -    QemuThread thread;
> -
> -    COCOA_DEBUG("Entered main()\n");
> -    gArgc = argc;
> -    gArgv = argv;
> +    [NSApp terminate:nil];
>   
> -    qemu_sem_init(&display_init_sem, 0);
> -    qemu_sem_init(&app_started_sem, 0);
> -
> -    qemu_thread_create(&thread, "qemu_main", call_qemu_main,
> -                       NULL, QEMU_THREAD_DETACHED);
> -
> -    COCOA_DEBUG("Main thread: waiting for display_init_sem\n");
> -    qemu_sem_wait(&display_init_sem);
> -    COCOA_DEBUG("Main thread: initializing app\n");
> -
> -    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
> -
> -    // Pull this console process up to being a fully-fledged graphical
> -    // app with a menubar and Dock icon
> -    ProcessSerialNumber psn = { 0, kCurrentProcess };
> -    TransformProcessType(&psn, kProcessTransformToForegroundApplication);
> -
> -    [QemuApplication sharedApplication];
> -
> -    create_initial_menus();
> +    return NULL;
> +}
>   
> -    /*
> -     * Create the menu entries which depend on QEMU state (for consoles
> -     * and removeable devices). These make calls back into QEMU functions,
> -     * which is OK because at this point we know that the second thread
> -     * holds the iothread lock and is synchronously waiting for us to
> -     * finish.
> -     */
> -    add_console_menu_entries();
> -    addRemovableDevicesMenuItems();
> +static void cocoa_main()
> +{
> +    COCOA_DEBUG("Entered %s()\n", __func__);
>   
> -    // Create an Application controller
> -    QemuCocoaAppController *appController = [[QemuCocoaAppController alloc] init];
> -    [NSApp setDelegate:appController];
> +    qemu_mutex_unlock_iothread();
> +    qemu_thread_create(&qemu_main_thread, "qemu_main", call_qemu_main,
> +                       NULL, QEMU_THREAD_JOINABLE);
>   
>       // Start the main event loop
>       COCOA_DEBUG("Main thread: entering OSX run loop\n");
>       [NSApp run];
>       COCOA_DEBUG("Main thread: left OSX run loop, exiting\n");
> -
> -    [appController release];
> -    [pool release];
> -
> -    return 0;
>   }
>   
>   
> @@ -2079,25 +1985,42 @@ static void cocoa_refresh(DisplayChangeListener *dcl)
>   
>   static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
>   {
> +    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
> +
>       COCOA_DEBUG("qemu_cocoa: cocoa_display_init\n");
>   
> -    /* Tell main thread to go ahead and create the app and enter the run loop */
> -    qemu_sem_post(&display_init_sem);
> -    qemu_sem_wait(&app_started_sem);
> -    COCOA_DEBUG("cocoa_display_init: app start completed\n");
> +    qemu_main = cocoa_main;
> +
> +    // Pull this console process up to being a fully-fledged graphical
> +    // app with a menubar and Dock icon
> +    ProcessSerialNumber psn = { 0, kCurrentProcess };
> +    TransformProcessType(&psn, kProcessTransformToForegroundApplication);
> +
> +    [QemuApplication sharedApplication];
> +
> +    create_initial_menus();
> +
> +    /*
> +     * Create the menu entries which depend on QEMU state (for consoles
> +     * and removeable devices). These make calls back into QEMU functions,
> +     * which is OK because at this point we know that the second thread
> +     * holds the iothread lock and is synchronously waiting for us to
> +     * finish.
> +     */
> +    add_console_menu_entries();
> +    addRemovableDevicesMenuItems();
> +
> +    // Create an Application controller
> +    QemuCocoaAppController *controller = [[QemuCocoaAppController alloc] init];
> +    [NSApp setDelegate:controller];
>   
> -    QemuCocoaAppController *controller = (QemuCocoaAppController *)[[NSApplication sharedApplication] delegate];
>       /* if fullscreen mode is to be used */
>       if (opts->has_full_screen && opts->full_screen) {
> -        dispatch_async(dispatch_get_main_queue(), ^{
> -            [NSApp activateIgnoringOtherApps: YES];
> -            [controller toggleFullScreen: nil];
> -        });
> +        [NSApp activateIgnoringOtherApps: YES];
> +        [controller toggleFullScreen: nil];
>       }
>       if (opts->u.cocoa.has_full_grab && opts->u.cocoa.full_grab) {
> -        dispatch_async(dispatch_get_main_queue(), ^{
> -            [controller setFullGrab: nil];
> -        });
> +        [controller setFullGrab: nil];
>       }
>   
>       if (opts->has_show_cursor && opts->show_cursor) {
> @@ -2117,6 +2040,8 @@ static void cocoa_display_init(DisplayState *ds, DisplayOptions *opts)
>       qemu_event_init(&cbevent, false);
>       cbowner = [[QemuCocoaPasteboardTypeOwner alloc] init];
>       qemu_clipboard_peer_register(&cbpeer);
> +
> +    [pool release];
>   }
>   
>   static QemuDisplay qemu_display_cocoa = {

This doesn't work for me:

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = 
EXC_BAD_ACCESS (code=1, address=0x18)
   * frame #0: 0x0000000100012bf0 
qemu-system-x86_64`update_displaychangelistener(dcl=0x00000001007d5f90, 
interval=16) at console.c:1671:14
     frame #1: 0x000000010001d150 qemu-system-x86_64`-[QemuCocoaView 
updateUIInfoLocked](self=<unavailable>, _cmd=<unavailable>) at 
cocoa.m:568:17
     frame #2: 0x00000001ae31d2a8 AppKit`-[NSView _setWindow:] + 2196
     frame #3: 0x00000001ae3266bc AppKit`-[NSView addSubview:] + 176
     frame #4: 0x00000001ae32d898 AppKit`-[NSFrameView addSubview:] + 52
     frame #5: 0x00000001ae32d84c AppKit`-[NSThemeFrame addSubview:] + 468
     frame #6: 0x00000001ae32d394 AppKit`-[NSView 
addSubview:positioned:relativeTo:] + 216
     frame #7: 0x00000001ae32d220 AppKit`-[NSThemeFrame 
addSubview:positioned:relativeTo:] + 52
     frame #8: 0x00000001ae32d1d4 AppKit`-[NSThemeFrame 
_addKnownSubview:positioned:relativeTo:] + 52
     frame #9: 0x00000001ae34d9a4 AppKit`-[NSWindow setContentView:] + 376
     frame #10: 0x000000010001e574 
qemu-system-x86_64`-[QemuCocoaAppController 
init](self=0x00006000000265f0, _cmd=<unavailable>) at cocoa.m:1230:9
     frame #11: 0x0000000100020be4 
qemu-system-x86_64`cocoa_display_init(ds=<unavailable>, 
opts=0x0000000100b5d678) at cocoa.m:2018:42
     frame #12: 0x00000001001c17b4 qemu-system-x86_64`qemu_init 
[inlined] qemu_init_displays at vl.c:2449:5
     frame #13: 0x00000001001c17a4 
qemu-system-x86_64`qemu_init(argc=<unavailable>, argv=<unavailable>) at 
vl.c:3566:5
     frame #14: 0x000000010000dc5c 
qemu-system-x86_64`main(argc=<unavailable>, argv=<unavailable>) at 
main.c:43:5
     frame #15: 0x000000010107108c dyld`start + 520

* thread #1, queue = 'com.apple.main-thread', stop reason = 
EXC_BAD_ACCESS (code=1, address=0x18)
     frame #0: 0x0000000100012bf0 
qemu-system-x86_64`update_displaychangelistener(dcl=0x00000001007d5f90, 
interval=16) at console.c:1671:14
    1668	    DisplayState *ds = dcl->ds;
    1669	
    1670	    dcl->update_interval = interval;
-> 1671	    if (!ds->refreshing && ds->update_interval > interval) {
    1672	        timer_mod(ds->gui_timer, ds->last_update + interval);
    1673	    }
    1674	}

(lldb) p ds
(DisplayState *) $0 = NULL

It seems what was discussed here:
https://lore.kernel.org/qemu-devel/89a0316d-7e9a-46d9-31cc-c3507483fffb@redhat.com/
register_displaychangelistener() not yet called.

Regards,

Phil.