Re: [Qemu-arm] [Qemu-devel] [Qemu-devel RFC v2 1/4] msf2: Add Smartfusion2 System timer

[sundeep subbaraya]

Hi Alistair and Peter,

On Mon, Apr 24, 2017 at 11:28 PM, Peter Maydell
<address@hidden> wrote:
> On 24 April 2017 at 18:44, Alistair Francis <address@hidden> wrote:
>> Basically the simple explanation is that init is called when the
>> object is created and realize is called when the object is realized.
>>
>> Generally for devices it will go something like this:
>>  1. init
>>  2. Set properties
>>  3. Connect things
>>  4. realize
>>  5. Map to memory
>>
>>> Don't we need to use realize function for new models?
>>
>> AFAIK we still put things like: sysbus_init_irq(),
>> memory_region_init_io() and sysbus_init_mmio() in the init function.
>>
>> I don't think we are at a stage yet to not use init functions.
>
> Two-phase init is here to stay -- some things must be done in
> init, some must be done in realize, and some can be done in
> either. Some simple devices may find they can do everything
> in only one function.
>
> Must be done in init:
>  * creating properties (for the cases where that is done "by hand"
>    by calling object_property_add_*())
>  * calling init on child objects which you want to pass through
>    alias properties for
>
> Must be done in realize:
>  * anything that can fail such that we need to report the
>    error and abandon creation of the device
>  * anything which depends on the values of QOM properties that
>    the caller might have set
>
> We should probably sit down and write up some guidelines for
> how we recommend dealing with the various things that could
> be called in either function -- this is basically a code
> style and consistency question.

Thanks for the brief. It makes sense for me now.
I will make changes and send the patches.

Thanks,
Sundeep

>
> thanks
> -- PMM