Re: [Qemu-devel] [RFC] QOM design - add instance data to Object (-> add constructors)

[Liviu Ionescu]

> On 13 Jun 2015, at 21:57, Liviu Ionescu <address@hidden> wrote:
> 
> ... so, no, the class structure is not suitable for multi-instances objects, 
> and even for singletons I think that using it for passing such configuration 
> data is generally abusive.

not to mention that in real life situations, constructors are used to pass 
non-static data, for example the 'machine' structure (for various command line 
params) when constructing MCUs, or the 'mcu' when constructing LEDs.

passing these pointers orderly to the entire hierarchy is very simple when 
using standard constructors.
 
how would you pass them with the existing .instance_init or .instance_post_init 
support? I don't think it is possible, which means the entire object 
construction needs to be delegated to realize(), which is way too late.


for a better understanding of the problem, I'm copying again the same (fully 
functional) code to create boards:

/* ----- Olimex STM32-H103 ----- */

GenericGPIOLEDInfo h103_machine_green_led = {
    .desc = "STM32-H103 Green LED, GPIOC[12], active low",
    .port_index = STM32_GPIO_PORT_C,
    .port_bit = 12,
    .active_low = true,
    .on_message = "[Green LED On]\n",
    .off_message = "[Green LED Off]\n",
    .use_stderr = true };

static void stm32_h103_board_init_callback(MachineState *machine)
{
    cortexm_board_greeting(machine);
    DeviceState *mcu = qdev_alloc(NULL, TYPE_STM32F103RB);
    {
        STM32F103RB_GET_CLASS(mcu)->construct(OBJECT(mcu), machine);

        /* Set the board specific oscillator frequencies. */
        DeviceState *rcc = stm32_mcu_get_rcc_dev(mcu);
        qdev_prop_set_uint32(rcc, "hse-freq-hz", 8000000); /* 8.0 MHz */
        qdev_prop_set_uint32(rcc, "lse-freq-hz", 32768); /* 32 KHz */
    }
    qdev_realize(mcu);

    /* Board peripheral objects */
    DeviceState *led = qdev_alloc(NULL, TYPE_STM32_GPIO_LED);
    {
        STM32_GPIO_LED_GET_CLASS(led)->construct(OBJECT(led),
                &h103_machine_green_led, mcu);
    }
    qdev_realize(led);
}

static QEMUMachine stm32_h103_machine = {
    .name = "STM32-H103",
    .desc = "Olimex Header Board for STM32F103RBT6 (Experimental)",
    .init = stm32_h103_board_init_callback };

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regards,

Liviu