Re: [Qemu-devel] [PATCH v2 3/3] exec.c: Collect AddressSpace related fields into a CPUAddressSpace struct

[Richard Henderson <rth@twiddle.net>]

On 10/08/2015 08:13 AM, Peter Maydell wrote:
> On 7 October 2015 at 10:57, Richard Henderson <rth@twiddle.net> wrote:
>> On 10/02/2015 12:29 AM, Peter Maydell wrote:
>>>
>>> +    cpu->cpu_ases = g_new0(CPUAddressSpace, 1);
>>> +    cpu->cpu_ases[0].cpu = cpu;
>>> +    cpu->cpu_ases[0].as = as;
>>> +    cpu->cpu_ases[0].tcg_as_listener.commit = tcg_commit;
>>> +    memory_listener_register(&cpu->cpu_ases[0].tcg_as_listener, as);
>>>    }
>>
>>
>> What's the plan when it's more than one?
>
> We g_realloc() the array to make it larger if the target-specific
> code calls us again to add another AS.
>
>> Just thinking about why separate allocation vs embedding an array.  Though
>> possibly with the CPUState member being a pointer to an array within the
>> TargetCPUClass, or CPUTargetState.  Dunno.
>
> An embedded array runs you into the problem that cpu.h doesn't
> have access to a definition of the MemoryListener struct (at
> least I think it's that one), so it doesn't know how much space
> to allocate in the structure. Plus MemoryListener doesn't
> exist in non-softmmu configs, and allowing the CPUState struct
> to be different sizes for softmmu vs not doesn't work because
> the header can be used from compiled-once-only .c files.
> This awkwardness is why we ended up with CPUState having a
> pointer to a MemoryListener and thus the loop in tcg_commit
> in the first place.

Ah, right.  Thanks.  Whole series

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~