[Qemu-devel] Is Little endian supported by Qemu -prep

[Qemu-devel] Is Little endian supported by Qemu -prep

[Tero Kaarlela]

Still working on OS/2 PPC edition bootloading. I got patch to ppc_prep.c 
from J Mayer to make it support non-continuous I/O map mode. It seemed 
to work ok. But catched bug in the further code after line mfspr 
r3,1008. I modified ppc_prep.c  Processor version from 0x00080000 (g3) 
to 0x00040000 (604) and problem was fixed. Now it crashes after code:

  subfic r0,r0,-32690
  mtlr r0
  blr
  (LR = ffef7f1e)
  r0 was 0x00100130 to begin with

  This error happens shortly after changinfg MSR state from 0x00000030 
to 0x00000031 (change mode from Big-endian to Little endian) So might 
 Little-endian be reason why LR goes nuts?:)



Tero Kaarlela

Re: [Qemu-devel] Is Little endian supported by Qemu -prep sorry wrong info!!

[Tero Kaarlela]

Tero Kaarlela wrote:

> Still working on OS/2 PPC edition bootloading. I got patch to 
> ppc_prep.c from J Mayer to make it support non-continuous I/O map 
> mode. It seemed to work ok. But catched bug in the further code after 
> line mfspr r3,1008. I modified ppc_prep.c  Processor version from 
> 0x00080000 (g3) to 0x00040000 (604) and problem was fixed. Now it 
> crashes after code:
>
>  subfic r0,r0,-32690
>  mtlr r0
>  blr
>  (LR = ffef7f1e)
>  r0 was 0x00100130 to begin with
>
>  This error happens shortly after changinfg MSR state from 0x00000030 
> to 0x00000031 (change mode from Big-endian to Little endian) So might 
> Little-endian be reason why LR goes nuts?:) 

Sorry I gave wrong info my mistake MSR state is changed from 0x00010030 
to 0x00000031 So DR & IR also affected

>
>
> Tero Kaarlela
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>

Re: [Qemu-devel] Is Little endian supported by Qemu -prep

[J. Mayer]

On Thu, 2005-04-07 at 10:02 +0300, Tero Kaarlela wrote:
> Still working on OS/2 PPC edition bootloading. I got patch to ppc_prep.c 
> from J Mayer to make it support non-continuous I/O map mode. It seemed 
> to work ok. But catched bug in the further code after line mfspr 
> r3,1008. I modified ppc_prep.c  Processor version from 0x00080000 (g3) 
> to 0x00040000 (604) and problem was fixed. Now it crashes after code:
> 
>   subfic r0,r0,-32690
>   mtlr r0
>   blr
>   (LR = ffef7f1e)
>   r0 was 0x00100130 to begin with
> 
>   This error happens shortly after changinfg MSR state from 0x00000030 
> to 0x00000031 (change mode from Big-endian to Little endian) So might 
>  Little-endian be reason why LR goes nuts?:)

Yes, that's the reason. As far as I know, Qemu has no support for
dynamic endian modes.
I did not think any OS did use LE mode...

Imho, the simple way to handle this is to add a bit in the translation
bloc state (flags in cpu-exec.c) and exend the memory access tables
(using mem_idx in target-ppc/translate.c) for little-endian case.
This is not so hard to do, but as all memory access routines have to be
duplicated, it may take some time to do the patch. The great thing doing
this way is that little endian mode will be as efficient as BE mode..
I'll take a look during the week end and give you a patch so you may go
on testing OS/2.

-- 
J. Mayer <l_indien@magic.fr>
Never organized

Re: [Qemu-devel] Is Little endian supported by Qemu -prep

[Tero Kaarlela]

J. Mayer wrote:

>On Thu, 2005-04-07 at 10:02 +0300, Tero Kaarlela wrote:
>  
>
>>Still working on OS/2 PPC edition bootloading. I got patch to ppc_prep.c 
>>from J Mayer to make it support non-continuous I/O map mode. It seemed 
>>to work ok. But catched bug in the further code after line mfspr 
>>r3,1008. I modified ppc_prep.c  Processor version from 0x00080000 (g3) 
>>to 0x00040000 (604) and problem was fixed. Now it crashes after code:
>>
>>  subfic r0,r0,-32690
>>  mtlr r0
>>  blr
>>  (LR = ffef7f1e)
>>  r0 was 0x00100130 to begin with
>>
>>  This error happens shortly after changinfg MSR state from 0x00000030 
>>to 0x00000031 (change mode from Big-endian to Little endian) So might 
>> Little-endian be reason why LR goes nuts?:)
>>    
>>
>
>Yes, that's the reason. As far as I know, Qemu has no support for
>dynamic endian modes.
>I did not think any OS did use LE mode...
>
Hmmm.. It seems that WinNT for PPC does run in Little-endian too...

>
>Imho, the simple way to handle this is to add a bit in the translation
>bloc state (flags in cpu-exec.c) and exend the memory access tables
>(using mem_idx in target-ppc/translate.c) for little-endian case.
>This is not so hard to do, but as all memory access routines have to be
>duplicated, it may take some time to do the patch. The great thing doing
>this way is that little endian mode will be as efficient as BE mode..
>I'll take a look during the week end and give you a patch so you may go
>on testing OS/2.
>
Thanks in advance once again :)

Re: [Qemu-devel] Is Little endian supported by Qemu -prep

[Gwenole Beauchesne]

Le jeudi, 7 avr 2005, à 18:29 Europe/Paris, Tero Kaarlela a écrit :

>> Yes, that's the reason. As far as I know, Qemu has no support for
>> dynamic endian modes.
>> I did not think any OS did use LE mode...
>>
> Hmmm.. It seems that WinNT for PPC does run in Little-endian too...

Yes too true. It's rumored that the NT kernel is highly portable but 
the Windows is definitely little endian and 32-bit oriented. Hence this 
unusual LLP64 model.

Re: [Qemu-devel] Is Little endian supported by Qemu -prep

[J. Mayer]

On Thu, 2005-04-07 at 19:46 +0200, Gwenole Beauchesne wrote:
> Le jeudi, 7 avr 2005, à 18:29 Europe/Paris, Tero Kaarlela a écrit :
> 
> >> Yes, that's the reason. As far as I know, Qemu has no support for
> >> dynamic endian modes.
> >> I did not think any OS did use LE mode...
> >>
> > Hmmm.. It seems that WinNT for PPC does run in Little-endian too...
> 
> Yes too true. It's rumored that the NT kernel is highly portable but 
> the Windows is definitely little endian and 32-bit oriented. Hence this 
> unusual LLP64 model.

Yes, right.
But WinNT is still far from booting and crashes, I think, before
checking/swapping the endian mode (don't try: I never commited the
needed patch to support it's own XCOFF format in Open Hack'Ware as I'm
sure it's buggy...)
Then, I add no example of little-endian run on PPC.
What I knew is that some say that VirtualPC use this mode to have a
faster emulation.

Now, it's obvious that the feature is needed.

-- 
J. Mayer <l_indien@magic.fr>
Never organized