Re: [Qemu-devel] [RFC PATCH v1 4/4] target-arm: Compute page size based on ARM target cpu type

[Vijay Kilari]

On Fri, Jun 17, 2016 at 1:12 AM, Richard Henderson <address@hidden> wrote:
> On 06/14/2016 04:36 AM, Peter Maydell wrote:
>> It would be better to delay the point at which we allocate
>> the data structures which care about page size, rather than
>> moving init of the CPU earlier.
>
> It would be *best* if we could re-initialize and re-allocate these data
> structures so that we can follow the current page size as it changes.
>
> Yes, this might require flushing just about everything, but it's the kind of
> thing that's likely to happen only at system startup.  After that, everything
> benefits from having the correct (larger) page size.

I tried shuffling the memory initialization code after cpu initialization.
but it was full mess. So could not proceed further.

However, I tried early creation cpu objects instead of doing it from
machvirt_init.
With this, initfn of the cpu model is called earlier and feature set is updated.
With that I could fetch arm architecture info. Based on this we can
choose page size.
I can send out RFC patch.

>
>> Also we should consider what happens if we have decided
>> the page size is X, and then a CPU is hotplugged which
>> requires a page size Y where Y < X.
>
> Is that a real possibility?  Or trivially true because the new cpu has yet to
> be initialized by the OS to use the regular OS page size.
>
>
> r~