Re: [Qemu-ppc] [PATCH] ppc: initialize GPRs as per epapr

[Scott Wood]

On 04/26/2013 01:59:10 AM, Alexander Graf wrote:
> On 26.04.2013, at 08:51, Bhushan Bharat-R65777 wrote:
>
> >
> >
> >> -----Original Message-----
> >> From: Alexander Graf [mailto:address@hidden
> >> Sent: Friday, April 26, 2013 11:51 AM
> >> To: Bhushan Bharat-R65777
> >> Cc: address@hidden; address@hidden; Wood Scott-B07421;  
> Bhushan
> >> Bharat-R65777; Yoder Stuart-B08248
> >> Subject: Re: [PATCH] ppc: initialize GPRs as per epapr
> >>
> >>
> >> On 26.04.2013, at 08:17, Bharat Bhushan wrote:
> >>
> >>> ePAPR defines the initial values of cpu registers. This patch
> >>> initialize the GPRs as per ePAPR specification.
> >>>
> >>> This resolves the issue of guest reboot/reset (guest hang on  
> reboot).
> >>
> >> Why does it hang only on reboot, not on initial bootup?
> >
> > may be memory pointed by env pointer are zero initialized initially.
> > Reboot also not always hangs. I have seen reboot mostly working on  
> e500v2/e500mc and mostly hanging on e5500.
>
> Yes, they're all zero initialized. I'm surprised that got things  
> working.

head_64.S assumes it's being booted from Open Firmware if r5 is  
non-zero -- this is why ePAPR requires r5 to be zero.

-Scott