Re: [Qemu-ppc] Regression in ppc-softmmu when running HelenOS

[Mark Cave-Ayland]

On 12/03/12 11:40, Alexander Graf wrote:

> > Hello,
> >
> > resending the bug report to qemu-ppc@ to get the potentially interested
> > people hooked:
> >
> > https://bugs.launchpad.net/qemu/+bug/942299
> >
> > The following commit introduced some change due to which HelenOS no
> > longer boots to command line:
>
> Could you please add printf's in that code path before and after the patch and 
> compare which bits are different in MSR? Maybe we screw up on maintaining 
> MSR_RI during interrupt delivery?
>
>
> Alex

I haven't managed to get as far as I liked on this to date (mainly as 
there was another bug preventing VGA in git master from PPC working), 
but I did manage to at least get HelenOS to boot with the (incomplete) 
attached patch against git master. I don't believe this is necessarily 
the full solution since I find the booted image is quite console 
lethargic (and can lose/return incorrect keypresses).

The reason I hadn't updated the bug was because I still wasn't sure if 
this was part of the QEMU performance regression I noticed when 
comparing old/new versions of HelenOS or simply because the flag 
handling for calculating new_msr is still incomplete. Some searching 
revealed the  link http://www.systemcomputing.org/ppc/ppc4.htm which 
seems to indicate that the MSR modification upon entry to the interrupt 
routine could be different to the list of always-zeroed flags removed by 
the mask (which is what pointed me in this direction in the first place).

Anyway, I include the patch as discussion point - don't forget that you 
need to boot QEMU with the openbios-ppc image from 0.11 stable branch if 
you currently wish to test this.


HTH,

Mark.

helenos-ppc.patch
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