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

[Mark Cave-Ayland]

On 06/11/14 18:23, Artyom Tarasenko wrote:

>> 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.

Hi Damien,

Great to see some interest in sun4u SMP support! I think Artyom's
summary above is about right - as a starting point you'll want to change
the sun4u init function to allow multiple CPUs and pass the details to
OpenBIOS so that more than one CPU node is added to the device tree.

With that in place I would expect multiple CPUs to be visible to the
guest, and so then it's a matter of implementing additional registers
required for CPU operation. As Artyom points out, there are still copies
of the old Sun documentation you can find lying around and I've also had
good support from the NetBSD/OpenBSD projects when trying to debug
low-level kernel issues during boot.

Feel free to CC me on any patches and I look forward to seeing the
results of your work :)


ATB,

Mark.