qmp 和 hmp

基本使用

• https://www.qemu.org/docs/master/devel/writing-monitor-commands.html
• https://wiki.qemu.org/Documentation/QMP
• https://www.qemu.org/docs/master/devel/writing-monitor-commands.html#writing-a-debugging-aid-returning-unstructured-text
• https://gist.github.com/rgl/dc38c6875a53469fdebb2e9c0a220c6c

qmp shell

• https://wiki.qemu.org/Documentation/QMP

qmp shell 常见命令:

1. query-cpu-definitions

qom-get

{ "execute": "qom-get",
             "arguments": { "path": "/machine/peripheral/balloon0",
             "property": "guest-stats" } }

• _start
  • __libc_start_main_impl
    • __libc_start_call_main
      • qemu_default_main
        • qemu_main_loop
          • main_loop_wait
            • os_host_main_loop_wait
              • glib_pollfds_poll
                • g_main_context_dispatch
                  • aio_ctx_dispatch
                    • aio_dispatch
                      • aio_bh_poll
                        • aio_bh_call
                          • do_qmp_dispatch_bh
                            • qmp_marshal_qom_get
                              • qmp_qom_get
                                • object_property_get_qobject
                                  • object_property_get
                                    • property_get_alias
                                      • object_property_get
                                        • balloon_stats_get_all

hmp

• 可以阅读的文档: 这里描述在 graphic 和 non-graphic 的模式下访问 HMI 的方法，并且说明了从 HMI 中间如何获取各种信息 https://web.archive.org/web/20180104171638/http://nairobi-embedded.org/qemu_monitor_console.html

源码分析

• hmp_info_balloon

• _start

  • __libc_start_main_impl
    • __libc_start_call_main
      • qemu_default_main
        • qemu_main_loop
          • main_loop_wait
            • os_host_main_loop_wait
              • glib_pollfds_poll
                • g_main_context_dispatch
                  • tcp_chr_read
                    • monitor_read
                      • readline_handle_byte
                        • monitor_command_cb
                          • handle_hmp_command
                            • handle_hmp_command_exec
                              • handle_hmp_command_exec
                                • hmp_info_balloon

void hmp_info_balloon(Monitor *mon, const QDict *qdict)
{
    BalloonInfo *info;
    Error *err = NULL;

    info = qmp_query_balloon(&err);
    if (hmp_handle_error(mon, err)) {
        return;
    }

    monitor_printf(mon, "balloon: actual=%" PRId64 "\n", info->actual >> 20);

    qapi_free_BalloonInfo(info);
}

• /home/martins3/core/qemu/build/hmp-commands-info.h 是如何生成的
• /home/martins3/core/qemu/build/qapi/qapi-commands-machine.h 中包含了 qmp_query_balloon

总结一些和 qobject 纠缠在一起的功能

• object_register_sugar_prop

static void qemu_process_sugar_options(void)
{
    if (mem_prealloc) {
        QObject *smp = qdict_get(machine_opts_dict, "smp");
        if (smp && qobject_type(smp) == QTYPE_QDICT) {
            QObject *cpus = qdict_get(qobject_to(QDict, smp), "cpus");
            if (cpus && qobject_type(cpus) == QTYPE_QSTRING) {
                const char *val = qstring_get_str(qobject_to(QString, cpus));
                object_register_sugar_prop("memory-backend", "prealloc-threads",
                                           val, false);
            }
        }
        object_register_sugar_prop("memory-backend", "prealloc", "on", false);
    }
}

如何快速定位到代码

hmp 中提供了一个 mce 命令，如何找到对应的实现:

hmp_mce 直接搜索 hmp_mce 即可

分析下

https://qemu.readthedocs.io/en/v8.1.5/interop/qemu-qmp-ref.html

hmp 中的 sendkey 是如何实现的

此外，相关配置: https://vncdotool.readthedocs.io/en/latest/usage.html

arm 上面没办法用，难道是这个问题? https://lists.gnu.org/archive/html/qemu-devel/2018-02/msg06218.html

qmp shell 中的命令可以看下

x-query-irq                        x-query-ramblock                   x-query-virtio-queue-element
x-query-jit                        x-query-roms                       x-query-virtio-queue-status
x-query-numa                       x-query-usb                        x-query-virtio-status
x-query-opcount                    x-query-virtio                     x-query-virtio-vhost-queue-status
(QEMU) x-query-irq
{"return": {"human-readable-text": "IRQ statistics for kvm-ioapic:\n 0: 13\n 1: 11\n 3: 2\n 4: 2\n 6: 3\n 8: 1\n10: 156\n12: 15\nIRQ statistics for kvm-i8259:\n 0: 13\n 1: 11\n 3: 2\n 4: 2\n 6: 3\n 8: 1\n10: 156\n12: 15\n"}}
(QEMU) x-query-jit
{"error": {"class": "GenericError", "desc": "JIT information is only available with accel=tcg"}}

也许有用

给Qemu虚拟机“打信号”：自定义QMP注入SCI中断 - MyStackTrace的文章 - 知乎 https://zhuanlan.zhihu.com/p/1943785816179607321

qmp ：没办法，不搞的话，dirty bitmap 是没有办法维持生活的

• grep 一下目前对于 qmp 的所有问题，尝试将 qmp 和 qemu option 融合一下
• https://gist.github.com/rgl/dc38c6875a53469fdebb2e9c0a220c6c
• https://wiki.qemu.org/Documentation/QMP

qmp

• qmp_block_commit 的唯一调用者是如何被生成的。
• OBJECT_DECLARE_SIMPLE_TYPE 是什么意思，和类似的 macro 有什么区别
• docs/devel/qapi-code-gen.txt 和 qmp 如何工作的，是如何生成的。

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