Re: [PATCH v2 08/13] rust: cleanup module_init!, use it from #[derive(Object)]

[Paolo Bonzini <pbonzini@redhat.com>]

On 10/25/24 10:59, Zhao Liu wrote:
> I want to see how general this macro could be, so I checked current
> type_init() cases for TypeInfo. In most cases, only type_register_static()
> is called directly in the init_fn() callback.

First of all, it's okay if the Rust code does not cover everything.  But 
looking at your cases:

> There are only two exceptions:
> 
> 1. Some init_fn callbacks contain more complex validation or register
> logic.
> 
>    For example, in backends/hostmem-epc.c, sgx_epc_backed_info involves
>    extra check before type_register_static().
> 
>    static void register_types(void)
>    {
>        int fd = qemu_open_old("/dev/sgx_vepc", O_RDWR);
>        if (fd >= 0) {
>            close(fd);
> 
>            type_register_static(&sgx_epc_backed_info);
>        }
>    }

This one is okay to just change to type_register_static(), moving the 
/dev/sgx_vepc code to the "complete" callback.

> 
>    And in hw/audio/intel-hda.c, there's extra pci_register_soundhw afer
>    type_register_static():
> 
>    static void intel_hda_register_types(void)
>    {
>        type_register_static(&hda_codec_bus_info);
>        type_register_static(&intel_hda_info);
>        type_register_static(&intel_hda_info_ich6);
>        type_register_static(&intel_hda_info_ich9);
>        type_register_static(&hda_codec_device_type_info);
>        pci_register_soundhw("hda", "Intel HD Audio", intel_hda_and_codec_init);
>    }
> 
>    The device can define a custom init_fn() for TypeInfo based on
>    module_init!, but I wonder if the examples above are valid. Is it
>    allowed to include other logic in init_fn()?

Yes, it is but it is also possible to use your own module_init! 
invocation outside #[derive(Object)].
> 2. Some init_fn callbacks use type_register() instead of
> type_register_static().
> 
>    TypeImpl *type_register_static(const TypeInfo *info)
>    {
>        return type_register(info);
>    }
> 
>    It seems that type_register() and type_register_static() are the same.
>    I guess I could clean up one of them, right? (type_register() was added
>    by your earlie commit 049cb3cfdac1 :-) ).

Yeah, you can!

Paolo