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

From: Mark Cave-Ayland
Subject: Re: [Qemu-ppc] Regression in ppc-softmmu when running HelenOS
Date: Mon, 12 Mar 2012 16:26:23 +0000
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20120207 Icedove/3.0.11

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


resending the bug report to qemu-ppc@ to get the potentially interested
people hooked:


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?


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.



Attachment: helenos-ppc.patch
Description: Text Data

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