a95291007b
The qapi_event_send_FOO() functions emit events like this:
QMPEventFuncEmit emit;
emit = qmp_event_get_func_emit();
if (!emit) {
return;
}
qmp = qmp_event_build_dict("FOO");
[put event arguments into @qmp...]
emit(QAPI_EVENT_FOO, qmp);
The value of qmp_event_get_func_emit() depends only on the program:
* In qemu-system-FOO, it's always monitor_qapi_event_queue.
* In tests/test-qmp-event, it's always event_test_emit.
* In all other programs, it's always null.
This is exactly the kind of dependence the linker is supposed to
resolve; we don't actually need an indirection.
Note that things would fall apart if we linked more than one QAPI
schema into a single program: each set of qapi_event_send_FOO() uses
its own event enumeration, yet they share a single emit function.
Which takes the event enumeration as an argument. Which one if
there's more than one?
More seriously: how does this work even now? qemu-system-FOO wants
QAPIEvent, and passes a function taking that to
qmp_event_set_func_emit(). test-qmp-event wants test_QAPIEvent, and
passes a function taking that to qmp_event_set_func_emit().
It works by type trickery, of course:
typedef void (*QMPEventFuncEmit)(unsigned event, QDict *dict);
void qmp_event_set_func_emit(QMPEventFuncEmit emit);
QMPEventFuncEmit qmp_event_get_func_emit(void);
We use unsigned instead of the enumeration type. Relies on both
enumerations boiling down to unsigned, which happens to be true for
the compilers we use.
Clean this up as follows:
* Generate qapi_event_send_FOO() that call PREFIX_qapi_event_emit()
instead of the value of qmp_event_set_func_emit().
* Generate a prototype for PREFIX_qapi_event_emit() into
qapi-events.h.
* PREFIX_ is empty for qapi/qapi-schema.json, and test_ for
tests/qapi-schema/qapi-schema-test.json. It's qga_ for
qga/qapi-schema.json, and doc-good- for
tests/qapi-schema/doc-good.json, but those don't define any events.
* Rename monitor_qapi_event_queue() to qapi_event_emit() instead of
passing it to qmp_event_set_func_emit(). This takes care of
qemu-system-FOO.
* Rename event_test_emit() to test_qapi_event_emit() instead of
passing it to qmp_event_set_func_emit(). This takes care of
tests/test-qmp-event.
* Add a qapi_event_emit() that does nothing to stubs/monitor.c. This
takes care of all other programs that link code emitting QMP events.
* Drop qmp_event_set_func_emit(), qmp_event_get_func_emit().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20181218182234.28876-3-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
[Commit message typos fixed]
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.
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:
mkdir build
cd build
../configure
make
Additional information can also be found online via the QEMU website:
https://qemu.org/Hosts/Linux
https://qemu.org/Hosts/Mac
https://qemu.org/Hosts/W32
Submitting patches
==================
The QEMU source code is maintained under the GIT version control system.
git clone https://git.qemu.org/git/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 HACKING and CODING_STYLE files.
Additional information on submitting patches can be found online via
the QEMU website
https://qemu.org/Contribute/SubmitAPatch
https://qemu.org/Contribute/TrivialPatches
The QEMU website is also maintained under source control.
git clone https://git.qemu.org/git/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:
$ 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:
$ 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 Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:
https://bugs.launchpad.net/qemu/
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 launchpad.
For additional information on bug reporting consult:
https://qemu.org/Contribute/ReportABug
Contact
=======
The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC
- 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://qemu.org/Contribute/StartHere
-- End