Re: [Qemu-devel] Adding SMP support for Sparc Target

[Artyom Tarasenko]

On Thu, Nov 6, 2014 at 6:36 PM, Damien Hilloulin
<address@hidden> wrote:
> Le 06/11/2014 16:27, Artyom Tarasenko a écrit :
>>
>> Hello Damien,
>>
>> On Thu, Nov 6, 2014 at 8:38 AM, Damien Hilloulin
>> <address@hidden> wrote:
>>>
>>> Hello everyone,
>>>
>>> I'm a newcomer in QEMU and my goal would be to port an existing system
>>> simulator using another emulator to QEMU.
>>> Some work has already been done, and Sparc has been the main target so
>>> far
>>> because of its simplicity (and because we have a very good support for
>>> Sparc
>>> with the other emulator).
>>> QEMU is great, open-source (contrary to the other emulator we have been
>>> using in the past), and that's why we are aiming at using it.
>>>
>>> However, it seems that the Sparc targets doesn't really support SMP/CMT
>>> as
>>> of now. So I am considering two possibilities:
>>> - adding SMP support in QEMU for the Sparc targets (and contribute it to
>>> QEMU :) )
>>
>> Do you mean a) emulating multiple guest cores on in a single host
>> thread, or b) emulating multiple guest cores in multiple host threads?
>
> a) Would be enough for us (but b) would be amazing) !
>>
>> The former (a) should be relative easy for a sun4m platform: just have
>> to put the CPUs at the proper place in the system bus and fill the CPU
>> Module Ids (MIDs) with the proper data.
>
> Could you please explain it with some more details? I don't really know how
> to do that (yet)...
> We are really interested in such a support for Sparc64, so I think that it
> would be for sun4u machines only.
> Would the changes would be the same or would there be more work?

Taking into account the overall status of sun4u emulation, it is a bit
more work.
AFAIR the SMP-related registers of Ultrasparc CPUs/chipsets are not implemented.
Additionally there are currently no sun4u SMP boards emulated in QEMU,
but I think this is a smaller issue.

Also some support in OpenBIOS might be necessary. Mark can surely tell more.

Artyom

-- 
Regards,
Artyom Tarasenko

SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu