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

From: Alexander Graf
Subject: Re: [Qemu-ppc] Regression in ppc-softmmu when running HelenOS
Date: Mon, 12 Mar 2012 20:33:24 +0100

On 12.03.2012, at 20:28, Jakub Jermar wrote:

> Hi Mark,
> On 03/12/2012 05:26 PM, Mark Cave-Ayland wrote:
>> 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.
> (Cc: to helenos-devel@)
> I tried your patch with the latest HelenOS mainline. The user experience
> seems the same compared to what you get with Qemu 0.11.1, meaning that
> in both cases the clock seems to go too fast (could be a HelenOS bug),
> but otherwise the system boots and runs fine.

So we are losing an MSR bit. Please try to find out which one it is.


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