Re: [Qemu-ppc] [PATCH v4 0/6] spapr/xics: fix migration of older machine types

[Nikunj A Dadhania]

Greg Kurz <address@hidden> writes:

> On Sun, 11 Jun 2017 17:38:42 +0800
> David Gibson <address@hidden> wrote:
>
>> On Fri, Jun 09, 2017 at 05:09:13PM +0200, Greg Kurz wrote:
>> > On Fri, 9 Jun 2017 20:28:32 +1000
>> > David Gibson <address@hidden> wrote:
>> >   
>> > > On Fri, Jun 09, 2017 at 11:36:31AM +0200, Greg Kurz wrote:  
>> > > > On Fri, 9 Jun 2017 12:28:13 +1000
>> > > > David Gibson <address@hidden> wrote:
>> > > >     
>> > > > > On Thu, Jun 08, 2017 at 03:42:32PM +0200, Greg Kurz wrote:    
>> > > > > > I've provided answers for all comments from the v3 review that I 
>> > > > > > deliberately
>> > > > > > don't address in v4.      
>> > > > > 
>> > > > > I've merged patches 1-4.  5 & 6 I'm still reviewing.
>> > > > >     
>> > > > 
>> > > > Cool. FYI, I forgot to mention that I only tested with KVM.
>> > > > 
>> > > > I'm now trying with TCG and I hit various guest crash on
>> > > > the destination (using your ppc-for-2.10 branch WITHOUT
>> > > > my patches):    
>> > > 
>> > > Drat.  What's your reproducer for this crash?
>> > >   
>> > 
>> > 1) start guest
>> > 
>> > qemu-system-ppc64 \
>> >  -nodefaults -nographic -snapshot -no-shutdown -serial mon:stdio \
>> >  -device virtio-net,netdev=netdev0,id=net0 \
>> >  -netdev 
>> > bridge,id=netdev0,br=virbr0,helper=/usr/libexec/qemu-bridge-helper \
>> >  -device virtio-blk,drive=drive0,id=blk0 \
>> >  -drive file=/home/greg/images/sle12-sp1-ppc64le.qcow2,id=drive0,if=none \
>> >  -machine type=pseries,accel=tcg -cpu POWER8

Strangely, your command line does not have multiple threads. Need to see
what is the side effect of enabling MTTCG by default here.

>> > 
>> > 2) migrate
>> > 
>> > 3) destination crashes (immediately or after very short delay) or
>> > hangs  
>> 
>> Ok.  I'll bisect it when I can, but you might well get to it first.
>> 
>> 
>
> Heh, maybe you didn't see in my mail but I did bisect:
>
> f0b0685d6694a28c66018f438e822596243b1250 is the first bad commit
> commit f0b0685d6694a28c66018f438e822596243b1250
> Author: Nikunj A Dadhania <address@hidden>
> Date:   Thu Apr 27 10:48:23 2017 +0530
>
>     tcg: enable MTTCG by default for PPC64 on x86

Let me have a look at it.

Regards,
Nikunj