如何在QEMU源代码中添加新设备？

Question

如何在QEMU源代码中添加新设备？

linuxkernelemulationhardwareqemu

21

使用QOM方法在qemu中仿真/添加新设备的步骤是什么？

与DeviceState/BusState和其他属性相关的更改应该在哪里进行？

- San

三，是什么类型的设备？ - osgx

2个回答

5

在2014年的“QOM exegesis and apocalypse”演示中，有一些例子，演示位于http://events.linuxfoundation.org/sites/events/files/slides/kvmforum14-qom_0.pdf

Creating an object

Object *o = object_new(TYPE_RNG_BACKEND_RANDOM);
object_property_set_str(o, "filename", "/dev/random", NULL);
object_property_set_bool(o, "opened", "true", NULL);
object_property_add_child(container_get("/somewhere"), "my-rng", o, NULL);
object_unref(o);

Inside properties

static bool rng_get_opened(Object *obj, Error **errp)
{
    RngBackend *s = RNG_BACKEND(obj);
    return s->opened;
}
static void rng_set_opened(Object *obj, bool value, Error **errp)
{
    RngBackend *s = RNG_BACKEND(obj);
    RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
    ...
    if (k->opened) {
        k->opened(s, errp)
    }
}
static void rng_backend_init(Object *obj)
{
    object_property_add_bool(obj, "opened",
        rng_get_opened, rng_set_opened, NULL);
}
static const TypeInfo rng_backend_info = {
   .name = TYPE_RNG_BACKEND,
   .parent = TYPE_OBJECT,
   .instance_size = sizeof(RngBackend),
   .instance_init = rng_backend_init,
   .class_size = sizeof(RngBackendClass),
   .abstract = true,
};

这两个页面可能有用： * http://wiki.qemu.org/Features/QOM * http://wiki.qemu.org/QOMConventions 请参照实际代码：http://code.metager.de/source/xref/qemu/backends/rng.c 和 RNG_BACKEND 的一个实现 http://code.metager.de/source/xref/qemu/backends/rng-random.c。

Siro Mugabi的文章“Essential QEMU PCI API”：http://nairobi-embedded.org/001_qemu_pci_device_essentials.html（http://web.archive.org/web/20151116022950/http://nairobi-embedded.org/001_qemu_pci_device_essentials.html）提供了一个完整的QOM-enabled PCI driver示例。

The QEMU Object Model (QOM) provides a framework for registering user creatable Types. QOM models buses, interfaces, devices, etc as types. In QOM, information by a user Type is used to create its ObjectClass instance as well as its Object instance. This information is specified in a TypeInfo structure (include/qom/object.h). For example:
/* hw/misc/pci-testdev.c */

static const TypeInfo pci_testdev_info = {
        .name          = TYPE_PCI_TEST_DEV,
        .parent        = TYPE_PCI_DEVICE,
        .instance_size = sizeof(PCITestDevState),
        .class_init    = pci_testdev_class_init,
};
where:

.name a string that indicates the user Type.

.parent a string that specifies the Type from which this user Type derives from.

.instance_size size of the Type's Object instance. Its allocation will be performed internally by QOM. Objects will be discussed in more detail in Section Object Instantiation.

.class_init the constructor hook. This function will be responsible for initializing the Type's ObjectClass instance.

- osgx

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可以查看英文原文，
原文链接

- Ciro Santilli OurBigBook.com · Accepted Answer

edu 是一个内置的教育PCI设备

它非常易于理解并且有很好的记录，所以我建议你去了解一下。

它暴露了一个最小的PCI设备，具有基本的IO、中断生成和DMA功能。

我写了一个最小的Linux内核模块+用户测试程序来使用它：

外置设备

我问过是否有可能在外部异步中制作out-of-tree设备：如何创建out-of-tree QEMU设备？但看起来不太可能。