Re: [PATCH 2/2] hyperv/synic: Allocate as ram_device

[Paolo Bonzini]

On 09/01/20 14:22, Dr. David Alan Gilbert wrote:
> * Michael S. Tsirkin (address@hidden) wrote:
>> On Thu, Jan 09, 2020 at 12:22:37PM +0000, Dr. David Alan Gilbert wrote:
>>> Do we want a new memory_region_init for that or just to be able to add
>>> a flag?
>>>
>> I think a flag API is preferable since this can apply to any kind of
>> region. But can go either way, Paolo's the maintainer there.
> 
> (Copying Paolo in)
> So what exactly does this flag mean; to me it's 'no vhost' - but is it
> actually more general?

It has two more effects in addition to no vhost:

1) it is skipped when dumping the guest (is this a good or bad idea for
SynIC?)

2) accesses to the region will use the specified size (e.g. 4-bytes for
address_space_stl, 1-byte for address_space_stb) instead of a memcpy.
Doesn't really matter for SynIC regions.

If (1) is a good idea, then it's 2 out of 3 and I guess the patch is okay.

Paolo