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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> |
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| configure | ||
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=========== QEMU README =========== QEMU is a generic and open source machine & userspace emulator and virtualizer. QEMU is capable of emulating a complete machine in software without any need for hardware virtualization support. By using dynamic translation, it achieves very good performance. QEMU can also integrate with the Xen and KVM hypervisors to provide emulated hardware while allowing the hypervisor to manage the CPU. With hypervisor support, QEMU can achieve near native performance for CPUs. When QEMU emulates CPUs directly it is capable of running operating systems made for one machine (e.g. an ARMv7 board) on a different machine (e.g. an x86_64 PC board). QEMU is also capable of providing userspace API virtualization for Linux and BSD kernel interfaces. This allows binaries compiled against one architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a different architecture ABI (e.g. the Linux x86_64 ABI). This does not involve any hardware emulation, simply CPU and syscall emulation. QEMU aims to fit into a variety of use cases. It can be invoked directly by users wishing to have full control over its behaviour and settings. It also aims to facilitate integration into higher level management layers, by providing a stable command line interface and monitor API. It is commonly invoked indirectly via the libvirt library when using open source applications such as oVirt, OpenStack and virt-manager. QEMU as a whole is released under the GNU General Public License, version 2. For full licensing details, consult the LICENSE file. Documentation ============= Documentation can be found hosted online at `<https://www.qemu.org/documentation/>`_. The documentation for the current development version that is available at `<https://www.qemu.org/docs/master/>`_ is generated from the ``docs/`` folder in the source tree, and is built by `Sphinx <https://www.sphinx-doc.org/en/master/>`_. Building ======== QEMU is multi-platform software intended to be buildable on all modern Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety of other UNIX targets. The simple steps to build QEMU are: .. code-block:: shell mkdir build cd build ../configure make Additional information can also be found online via the QEMU website: * `<https://wiki.qemu.org/Hosts/Linux>`_ * `<https://wiki.qemu.org/Hosts/Mac>`_ * `<https://wiki.qemu.org/Hosts/W32>`_ Submitting patches ================== The QEMU source code is maintained under the GIT version control system. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu.git When submitting patches, one common approach is to use 'git format-patch' and/or 'git send-email' to format & send the mail to the qemu-devel@nongnu.org mailing list. All patches submitted must contain a 'Signed-off-by' line from the author. Patches should follow the guidelines set out in the `style section <https://www.qemu.org/docs/master/devel/style.html>`_ of the Developers Guide. Additional information on submitting patches can be found online via the QEMU website: * `<https://wiki.qemu.org/Contribute/SubmitAPatch>`_ * `<https://wiki.qemu.org/Contribute/TrivialPatches>`_ The QEMU website is also maintained under source control. .. code-block:: shell git clone https://gitlab.com/qemu-project/qemu-web.git * `<https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/>`_ A 'git-publish' utility was created to make above process less cumbersome, and is highly recommended for making regular contributions, or even just for sending consecutive patch series revisions. It also requires a working 'git send-email' setup, and by default doesn't automate everything, so you may want to go through the above steps manually for once. For installation instructions, please go to: * `<https://github.com/stefanha/git-publish>`_ The workflow with 'git-publish' is: .. code-block:: shell $ git checkout master -b my-feature $ # work on new commits, add your 'Signed-off-by' lines to each $ git publish Your patch series will be sent and tagged as my-feature-v1 if you need to refer back to it in the future. Sending v2: .. code-block:: shell $ git checkout my-feature # same topic branch $ # making changes to the commits (using 'git rebase', for example) $ git publish Your patch series will be sent with 'v2' tag in the subject and the git tip will be tagged as my-feature-v2. Bug reporting ============= The QEMU project uses GitLab issues to track bugs. Bugs found when running code built from QEMU git or upstream released sources should be reported via: * `<https://gitlab.com/qemu-project/qemu/-/issues>`_ If using QEMU via an operating system vendor pre-built binary package, it is preferable to report bugs to the vendor's own bug tracker first. If the bug is also known to affect latest upstream code, it can also be reported via GitLab. For additional information on bug reporting consult: * `<https://wiki.qemu.org/Contribute/ReportABug>`_ ChangeLog ========= For version history and release notes, please visit `<https://wiki.qemu.org/ChangeLog/>`_ or look at the git history for more detailed information. Contact ======= The QEMU community can be contacted in a number of ways, with the two main methods being email and IRC: * `<mailto:qemu-devel@nongnu.org>`_ * `<https://lists.nongnu.org/mailman/listinfo/qemu-devel>`_ * #qemu on irc.oftc.net Information on additional methods of contacting the community can be found online via the QEMU website: * `<https://wiki.qemu.org/Contribute/StartHere>`_