KVM on MIPS?

KVM on MIPS?

[Dale Farnsworth]

I'm beginning to look at implementing KVM on MIPS.  I've tried to search
for any work-in-progress on this but haven't found much at all.

If you know of anyone who is working on this or of pitfalls I should
consider before jumping in, please let me know.

Thanks,
-Dale

Re: KVM on MIPS?

[Avi Kivity]

On 03/25/2010 06:54 PM, Dale Farnsworth wrote:
> I'm beginning to look at implementing KVM on MIPS.  I've tried to search
> for any work-in-progress on this but haven't found much at all.
>    

Google comes up with some hits, but nothing concrete.

> If you know of anyone who is working on this or of pitfalls I should
> consider before jumping in, please let me know.
>    

Is the instruction set virtualizable?  Are you planning full virt or 
paravirt?

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

Re: KVM on MIPS?

[Alexander Graf]

Am 25.03.2010 um 22:04 schrieb Avi Kivity <avi@redhat.com>:

> On 03/25/2010 06:54 PM, Dale Farnsworth wrote:
>> I'm beginning to look at implementing KVM on MIPS.  I've tried to  
>> search
>> for any work-in-progress on this but haven't found much at all.
>>
>
> Google comes up with some hits, but nothing concrete.
>
>> If you know of anyone who is working on this or of pitfalls I should
>> consider before jumping in, please let me know.
>>
>
> Is the instruction set virtualizable?

FWIW it's not. Kernel mode is used based on an address offset of the  
IP. Since you'd want to have your guest running in user mode, you're  
pretty much lost there.


Alex

> Are you planning full virt or paravirt?
>
> -- 
> Do not meddle in the internals of kernels, for they are subtle and  
> quick to panic.
>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: KVM on MIPS?

[Dale Farnsworth]

On Thu, Mar 25, 2010 at 11:32:57PM +0100, Alexander Graf wrote:
>
> Am 25.03.2010 um 22:04 schrieb Avi Kivity <avi@redhat.com>:
>
>> On 03/25/2010 06:54 PM, Dale Farnsworth wrote:
>>> I'm beginning to look at implementing KVM on MIPS.  I've tried to  
>>> search
>>> for any work-in-progress on this but haven't found much at all.
>>
>>> If you know of anyone who is working on this or of pitfalls I should
>>> consider before jumping in, please let me know.
>>>
>>
>> Is the instruction set virtualizable?
>
> FWIW it's not. Kernel mode is used based on an address offset of the IP. 
> Since you'd want to have your guest running in user mode, you're pretty 
> much lost there.

I guess that would qualify as a pitfall.  Thanks Avi and Alex.

-Dale

Re: KVM on MIPS?

[Dale Farnsworth]

On Fri, Mar 26, 2010 at 09:16:19AM -0700, Dale Farnsworth wrote:
> On Thu, Mar 25, 2010 at 11:32:57PM +0100, Alexander Graf wrote:
> >
> > Am 25.03.2010 um 22:04 schrieb Avi Kivity <avi@redhat.com>:
> >
> >> On 03/25/2010 06:54 PM, Dale Farnsworth wrote:
> >>> I'm beginning to look at implementing KVM on MIPS.  I've tried to  
> >>> search
> >>> for any work-in-progress on this but haven't found much at all.
> >>
> >>> If you know of anyone who is working on this or of pitfalls I should
> >>> consider before jumping in, please let me know.
> >>>
> >>
> >> Is the instruction set virtualizable?
> >
> > FWIW it's not. Kernel mode is used based on an address offset of the IP. 
> > Since you'd want to have your guest running in user mode, you're pretty 
> > much lost there.
> 
> I guess that would qualify as a pitfall.  Thanks Avi and Alex.

After thinking about this some more, I think this means we can't run
an unmodified guest.  It should be possible to build the guest kernel
to run in supervisor or user mode/address space.

I'm new to MIPS, so I'm still looking for other challenges in virtualizing
the instruction set.

-Dale

Re: KVM on MIPS?

[Nolan]

Dale Farnsworth <dale <at> farnsworth.org> writes:
> After thinking about this some more, I think this means we can't run
> an unmodified guest.  It should be possible to build the guest kernel
> to run in supervisor or user mode/address space.
> 
> I'm new to MIPS, so I'm still looking for other challenges in virtualizing
> the instruction set.

You might want to read "Disco: Running Commodity Operating Systems on Scalable
Multiprocessors" by the folks at Stanford who eventually went on to write VMware.

They wrote a VMM for a MIPS ccNUMA.  IIRC, they had to both do binary
translation, as well as relink Irix to live at an address in the user KSEG,
instead the kernel KSEG.

- nolan

Re: KVM on MIPS?

[Hollis Blanchard]

On 03/26/2010 12:59 PM, Dale Farnsworth wrote:
> On Fri, Mar 26, 2010 at 09:16:19AM -0700, Dale Farnsworth wrote:
>> On Thu, Mar 25, 2010 at 11:32:57PM +0100, Alexander Graf wrote:
>>>
>>> Am 25.03.2010 um 22:04 schrieb Avi Kivity<avi@redhat.com>:
>>>
>>>> On 03/25/2010 06:54 PM, Dale Farnsworth wrote:
>>>>> I'm beginning to look at implementing KVM on MIPS.  I've tried to
>>>>> search
>>>>> for any work-in-progress on this but haven't found much at all.
>>>>
>>>>> If you know of anyone who is working on this or of pitfalls I should
>>>>> consider before jumping in, please let me know.
>>>>>
>>>>
>>>> Is the instruction set virtualizable?
>>>
>>> FWIW it's not. Kernel mode is used based on an address offset of the IP.
>>> Since you'd want to have your guest running in user mode, you're pretty
>>> much lost there.
>>
>> I guess that would qualify as a pitfall.  Thanks Avi and Alex.
>
> After thinking about this some more, I think this means we can't run
> an unmodified guest.  It should be possible to build the guest kernel
> to run in supervisor or user mode/address space.
>
> I'm new to MIPS, so I'm still looking for other challenges in virtualizing
> the instruction set.

Hi Dale, how is this going?

Hollis Blanchard
Mentor Graphics, Embedded Systems Division

Re: KVM on MIPS?

[Dale Farnsworth]

On Thu, Aug 12, 2010 at 02:26:17PM -0700, Hollis Blanchard wrote:
> On 03/26/2010 12:59 PM, Dale Farnsworth wrote:
>> On Fri, Mar 26, 2010 at 09:16:19AM -0700, Dale Farnsworth wrote:
>>> On Thu, Mar 25, 2010 at 11:32:57PM +0100, Alexander Graf wrote:
>>>>
>>>> Am 25.03.2010 um 22:04 schrieb Avi Kivity<avi@redhat.com>:
>>>>
>>>>> On 03/25/2010 06:54 PM, Dale Farnsworth wrote:
>>>>>> I'm beginning to look at implementing KVM on MIPS.  I've tried to
>>>>>> search
>>>>>> for any work-in-progress on this but haven't found much at all.
>>>>>
>>>>>> If you know of anyone who is working on this or of pitfalls I should
>>>>>> consider before jumping in, please let me know.
>>>>>>
>>>>>
>>>>> Is the instruction set virtualizable?
>>>>
>>>> FWIW it's not. Kernel mode is used based on an address offset of the IP.
>>>> Since you'd want to have your guest running in user mode, you're pretty
>>>> much lost there.
>>>
>>> I guess that would qualify as a pitfall.  Thanks Avi and Alex.
>>
>> After thinking about this some more, I think this means we can't run
>> an unmodified guest.  It should be possible to build the guest kernel
>> to run in supervisor or user mode/address space.
>>
>> I'm new to MIPS, so I'm still looking for other challenges in virtualizing
>> the instruction set.
>
> Hi Dale, how is this going?
>
> Hollis Blanchard
> Mentor Graphics, Embedded Systems Division

Unfortunately, I haven't been able to spend much time on it.
So, it's not really going.

-Dale