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

[Tero Kaarlela <turo.kaarlela@co.inet.fi>]

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 :)