Re: [Qemu-devel] git bisect results: ec757c67c40a56492001487e69272f62144fd124 breaks windows boot in qemu-kvm

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-02-01 16:43, Erik Rull wrote:
>  On February 1, 2012 at 3:42 PM Jan Kiszka <jan.kiszka@siemens.com> wrote:
> 
>> On 2012-02-01 15:02, Erik Rull wrote:
>>>
>>> On February 1, 2012 at 2:40 PM Avi Kivity <avi@redhat.com> wrote:
>>>
>>>> On 02/01/2012 02:52 PM, Erik Rull wrote:
>>>>>  Hi all,
>>>>>
>>>>> first of all I'm a bit confused:
>>>>>
>>>>> What is the difference between qemu with command line option
>>> --enable-kvm
>>>>> and qemu-kvm?
>>>>> It seems to be a difference in code so far, from the performance
> point
>>> of
>>>>> view it seems to be the same...
>>>>
>>>> The differences are being reduced rapidly, thanks to Jan's efforts.
>>>> Right now what remains is PIT performance and accuracy, device
>>>> assignment, and Windows XP performance.  Most guests should see the
> same
>>>> performance.
>>
>> MSI performance is expected to be worse with upstream as well, thus
> virtio.
>>
>>>>
>>>>> Now my issue that lead me to a git bisect on qemu-kvm:
>>>>> The following commit / merge breaks my windows guest boot sequence
> and
>>>>> causes resets infinitely:
>>>>> ec757c67c40a56492001487e69272f62144fd124 Merge branch
> 'upstream-merge'
>>> into
>>>>> next

So commit aad3b517a1b83561f2755dc4451596a421399c19, i.e. the last merge
before that one is still fine?

>>>>> Thu, 5 Jan 2012 11:00:07 +0000 (13:00 +0200)    Avi Kivity
>>> <avi@redhat.com>
>>>>>
>>>>>
>>>>> Interesting: qemu with --enable-kvm master and the same command line
>>>>> options as qemu-kvm runs perfect.
>>>>> My command line options are:
>>>>> qemu-system-x86_64 -serial /dev/ttyS2 -readconfig
>>> /etc/ich9-ehci-uhci.cfg
>>>>> -device usb-host,bus=ehci.0 -device usb-tablet -drive
>>>>> file=/dev/sda2,cache=off -m 1024 -net nic,macaddr=$MACADDR -net
>>>>> tap,script=/etc/qemu-ifup -no-acpi -monitor stdio -L
>>> /usr/X11R6/share/qemu
>>>>> -boot c -localtime
>>>>>
>>>>>
>>>>
>>>> What version of Windows are you using?  What's the contents of
>>>> /etc/ich9-ehci-uhci.cfg?
>>>>
>>>
>>> Hi Avi,
>>>
>>> the contents from the .cfg are located in docs/ich9-ehci-uhci.cfg
>>>
>>> I tried two versions of Windows XP: One is the default Windows XP SP3
> that
>>> you get from MSDN, one is Windows Embedded Standard (embedded
> customized
>>> XP).
>>>
>>> Both show the same behavior: boots with qemu -enable-kvm and
> continuously
>>> reboots with qemu-kvm.
>>
>> What does qemu-kvm with -no-kvm-irqchip do?
>>
>> Jan
>>
> 
> Wow - that works!
> Does this influence the guest performance?
> 

Yes, how much depends on your workload.

Still strange, though. We should try to understand this issue. It stays
like this up to and including current qemu-kvm.git master?

Jan

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