On MacOS, UI event loop has to be ran in the main thread of a process.
Because of that restriction, on this platform, qemu main event loop is
ran on another thread [1].
This breaks record/replay feature, which expects thread running qemu_init
to initialize hold this lock, breaking associated functional tests on
MacOS.
Thus, as a generalization, and similar to how BQL is handled, we release
it after init, and reacquire the lock before entering main event loop,
avoiding a special case if a separate thread is used.
Tested on MacOS with:
$ meson test -C build --setup thorough --print-errorlogs \
func-x86_64-x86_64_replay func-arm-arm_replay func-aarch64-aarch64_replay
$ ./build/qemu-system-x86_64 -nographic -icount shift=auto,rr=record,rrfile=replay.log
$ ./build/qemu-system-x86_64 -nographic -icount shift=auto,rr=replay,rrfile=replay.log
[1] f5ab12caba
Fixes: https://gitlab.com/qemu-project/qemu/-/issues/2907
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250410225550.46807-2-pierrick.bouvier@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
macOS's Cocoa event handling must be done on the initial (main) thread
of the process. Furthermore, if library or application code uses
libdispatch, the main dispatch queue must be handling events on the main
thread as well.
So far, this has affected Qemu in both the Cocoa and SDL UIs, although
in different ways: the Cocoa UI replaces the default qemu_main function
with one that spins Qemu's internal main event loop off onto a
background thread. SDL (which uses Cocoa internally) on the other hand
uses a polling approach within Qemu's main event loop. Events are
polled during the SDL UI's dpy_refresh callback, which happens to run
on the main thread by default.
As UIs are mutually exclusive, this works OK as long as nothing else
needs platform-native event handling. In the next patch, a new device is
introduced based on the ParavirtualizedGraphics.framework in macOS.
This uses libdispatch internally, and only works when events are being
handled on the main runloop. With the current system, it works when
using either the Cocoa or the SDL UI. However, it does not when running
headless. Moreover, any attempt to install a similar scheme to the
Cocoa UI's main thread replacement fails when combined with the SDL
UI.
This change tidies up main thread management to be more flexible.
* The qemu_main global function pointer is a custom function for the
main thread, and it may now be NULL. When it is, the main thread
runs the main Qemu loop. This represents the traditional setup.
* When non-null, spawning the main Qemu event loop on a separate
thread is now done centrally rather than inside the Cocoa UI code.
* For most platforms, qemu_main is indeed NULL by default, but on
Darwin, it defaults to a function that runs the CFRunLoop.
* The Cocoa UI sets qemu_main to a function which runs the
NSApplication event handling runloop, as is usual for a Cocoa app.
* The SDL UI overrides the qemu_main function to NULL, thus
specifying that Qemu's main loop must run on the main
thread.
* The GTK UI also overrides the qemu_main function to NULL.
* For other UIs, or in the absence of UIs, the platform's default
behaviour is followed.
This means that on macOS, the platform's runloop events are always
handled, regardless of chosen UI. The new PV graphics device will
thus work in all configurations. There is no functional change on other
operating systems.
Implementing this via a global function pointer variable is a bit
ugly, but it's probably worth investigating the existing UI thread rule
violations in the SDL (e.g. #2537) and GTK+ back-ends. Fixing those
issues might precipitate requirements similar but not identical to those
of the Cocoa UI; hopefully we'll see some kind of pattern emerge, which
can then be used as a basis for an overhaul. (In fact, it may turn
out to be simplest to split the UI/native platform event thread from the
QEMU main event loop on all platforms, with any UI or even none at all.)
Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Tested-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20241223221645.29911-2-phil@philjordan.eu>
[PMD: Declare 'qemu_main' symbol in tests/qtest/fuzz/fuzz.c,
add missing g_assert_not_reached() call in main()]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Headers in include/sysemu/ are not only related to system
*emulation*, they are also used by virtualization. Rename
as system/ which is clearer.
Files renamed manually then mechanical change using sed tool.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Lei Yang <leiyang@redhat.com>
Message-Id: <20241203172445.28576-1-philmd@linaro.org>
gdb_exit function aims to close gdb sessions and sends the exit code of
the current execution. It's being called by qemu_cleanup once the main
loop is over.
Until now, the exit code sent was always 0. Now that hardware can
shutdown this main loop with custom exit codes, these codes must be
transfered to gdb as well.
Signed-off-by: Clément Chigot <chigot@adacore.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231003071427.188697-3-chigot@adacore.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
The softmmu/ directory contains files specific to system
emulation. Rename it as system/. Update meson rules, the
MAINTAINERS file and all the documentation and comments.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20231004090629.37473-14-philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
