Re: [Qemu-devel] [PATCH 0/6] refactor PC machine, i440fx and piix3 to take advantage of QOM

[Jan Kiszka]

On 2012-03-26 04:06, Wanpeng Li wrote:
> From: Anthony Liguori <address@hidden>
> 
> 
> This series aggressively refactors the PC machine initialization to be more
> modelled and less ad-hoc.  The highlights of this series are:
> 
>  1) Things like -m and -bios-name are now device model properties
> 
>  2) The i440fx and piix3 are now modelled in a thorough fashion
> 
>  3) Most of the chipset features of the piix3 are modelled through composition
> 
>  4) i440fx_init is trivialized to creating devices and setting properties
> 
>  5) convert MemoryRegion to QOM
> 
>  6) convert PCI host bridge to QOM
> 
> The point (4) is the most important one.  As we refactor in this fashion,
> we should quickly get to the point where machine->init disappears completely 
> in
> favor of just creating a handful of devices.
> 
> The two stage initialization of QOM is important here.  instance_init() is 
> when
> composed devices are created which means that after you've created a device, 
> all
> of its children are visible in the device model.  This lets you set properties
> of the parent and its children.
> 
> realize() (which is still called DeviceState::init today) will be called right
> before the guest starts up for the first time.

While I see the value of the overall direction, I still disagree on
making internal data structures of HPET, RTC and 8254 publicly
available. That's a wrong step back. I'm sure there are smarter
solutions, alse as there were some proposals back then in the original
thread.

I'm also sure we will have to refactor the merge significantly again for
the introduction of additional chipsets and PC boards. But unless those
requirements can already be specified (Isaku?), that might be unavoidable.

Jan

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