Re: [Qemu-devel] [PATCH v4 3/4] hw/arm: add sunxi machine type

[Li Guang <lig.fnst@cn.fujitsu.com>]

Peter Maydell wrote:
> On 29 November 2013 08:06, Li Guang<lig.fnst@cn.fujitsu.com>  wrote:
>    
>> what I design is:
>> we have a sunxi series as a machine, then
>> for sunx4i, we specify -M sunxi -cpu cortex-a8 -device x1 ...
>> for sunx5i, we specify -M sunxi -cpu cortex-a8 -device x2 ...
>> for sunx7i, we specify -M sunxi -cpu cortex-a7 -devcie x3 ...
>> for cubieboard, we specify -M sunxi -cpu -cortex-a8 -device x1 -device p1
>>      
> No, QEMU doesn't work this way. "-M whatever" specifies a board
> model, so in this example it should be "-M cubieboard" and so on.
> That then gives you a particular CPU and set of devices. Obviously
> where we have several board models that share a single SoC they
> share implementation (by instantiating the same SoC object).
> If we have several SoCs that share common subcomponents like
> a UART, then they share implementation by having all those SoCs
> instantiate the same UART object.
>
> -cpu is really only intended where you have a situation like the
> PC where just the CPU can be plugged and unplugged into a
> board; it doesn't fit for SoC-based systems.
> Similarly, -device is really (currently) for pluggable devices like
> ISA or PCI cards -- where the device is a non-removable
> part of the SoC it doesn't work.
>    

why not just say this SoC is a board?
and other board like cubieboard are only
this SoC + several devices,
I think is reasonable, at least in this case.

A10 and A13 both have a cortex-a8, different in HDMI and SATA,
suppose we modeled A10, A10State,
if we add cubieboard, we realize A10,
then we have a board called demoboard based on A13,
what we will do here?
also realize A10?  unlucky, we miss HDMI and SATA difference,
model A13? new a A13State?
but we have most devices the same for A10 & A13.


> As Andreas says, we need to model real actual hardware,
> not some abstraction that kind of matches the kernel's
> abstractions.
>    

I never aimed to do what you said abstraction,
I just specified a represented of real hardware.

> Is "sunxi" what the hardware is actually called, or only
> what the kernel port has been called? More information
> about where this name comes from might make it easier
> to tell if it is the correct one for the QEMU SoC models.
>
>
>    

I tried to contact Allwinner's engineer,
no response until now.

Thanks!
Li Guang