Re: [Qemu-devel] [RFC PATCH v1 07/11] memory.c: Add address_space_init_shareable()

[Peter Crosthwaite]

On Wed, Jun 4, 2014 at 1:30 AM, Peter Maydell <address@hidden> wrote:
> On 3 June 2014 03:10, Peter Crosthwaite <address@hidden> wrote:
>> This will either create a new AS or return a pointer to an
>> already existing equivalent one. Both name and root mr must
>> match.
>>
>> The motivation is to reuse address spaces as much as possible.
>> Its going to be quite common that bus masters out in device land
>> have pointers to the same memory region for their mastering yet
>> each will need to create its own address space. Let the memory
>> API implement sharing for them.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>> ---
>> I know this leaks memory. I'll fix that post RFC. I think we need
>> AS ref counters to do it properly if anyone has any input on how
>> that should be done.
>>
>> We could change the equivalency test only match mr to support device
>> specific naming of these shared ASes. The singleton AS can ultimately
>> only have one name however. So perhaps some strcatting each time a new
>> sharer is added to the share. That or first-in-best-dressed.
>
> Is this here because it looked like it would be really easy
> to do, or because you tried this series without shared ASes
> and found it was too inefficient?
>

Because it look easy. Although less actual as's means less info mtree
output. I would suspect that tool is un-usable without shared AS.

Regards,
Peter

> thanks
> -- PMM
>