Re: [Qemu-ppc] QEMU PowerPC 464 User Mode Support

[David Gibson]

On Thu, Sep 29, 2016 at 06:29:07AM +0000, Sanjiv Doshi (sandoshi) wrote:
> David
> Appreciate your I/p.
> 
> I did try to enable 460 as you suggested. However when you look at 
> cpu-models.h file you find that it is not complete for 460 core:
> 
> ========== snippet from cpu-models.h ========
> 
>    /* PowerPC 460 family */                                                   
>                  |                                                            
>                                      
> #if 0                                                                         
>                   |                                                           
>                                       
>     /* Generic PowerPC 464 */                                                 
>                   |                                                           
>                                       
> #define CPU_POWERPC_464              CPU_POWERPC_464H90                       
>                   |                                                           
>                                       
> #endif                                                                        
>                   |                                                           
>                                       
>     /* PowerPC 464 microcontrolers */                                         
>                   |                                                           
>                                       
> #if 0                                                                         
>                   |                                                           
>                                       
>     CPU_POWERPC_464H90             = xxx,                                     
>                   |                                                           
>                                       
> #endif                                                                        
>                   |                                                           
>                                       
> #if 0                                                                         
>                   |                                                           
>                                       
>     CPU_POWERPC_464H90FP           = xxx,                                     
>                   |                                                           
>                                       
> #endif                                                                        
>                   |                                                           
>                                       
> 
> ===========================
> 
> Please pardon my ignorance of powerpc architecture and qemu but from
> “xxx” seem to point that the code is in-complete. Do you have any
> suggestions?

Ah, good point.  Looks like someone put in the entries for reference,
but no-one's actually implemented it.

In that case one of the 440 variants is probably your closest starting
point.  To get a full softmmu implementation would likely be a fair
bit of work, but just userspace emu should be a lot simpler.

> Thanks - Sanjiv
> 
> 
> 
> On 9/28/16, 9:22 PM, "David Gibson" <address@hidden> wrote:
> 
> >On Thu, Sep 29, 2016 at 12:10:38AM +0000, Sanjiv Doshi (sandoshi) wrote:
> >> Folks
> >
> >> We are looking for qemu user mode emulation support for PowerPC 464
> >> core.
> >
> >> Has anyone done any work for this core? What is the nearest PowerPC
> >> core that is currently supported in user mode that closely resembles
> >> 464. We have tried 440GX but does not solve all use cases.
> >
> >A quick look at the code suggests 460 and 460F CPUs are defined, which
> >are probably the closest to what you want.  However, I don't know how
> >complete it is.  I don't know that anyone is active working on any
> >kind of 44x or 46x emulation, unfortunately.
> >
> >Since you're only looking at user mode emulation, the number of
> >changes should be relatively small (the big differences between
> >powerpc cores are at the supervisor / mmu level).
> >
> >If you're willing, I think the way forward would be to try using the
> >460 CPU, see what instructions aren't working and fix or add them as
> >you find them.  Unfortunately, I can't really estimate of how big a
> >job that will be.
> >
> >Also be aware that if you did that, you'd probably end up as ppc 46x
> >maintainer by default..
> >

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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