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Re: [Qemu-devel] machines and versions - why so many?
From: |
Alexey Kardashevskiy |
Subject: |
Re: [Qemu-devel] machines and versions - why so many? |
Date: |
Tue, 24 Jun 2014 15:37:32 +1000 |
User-agent: |
Mozilla/5.0 (X11; Linux i686 on x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 |
On 06/24/2014 03:15 PM, Paolo Bonzini wrote:
> Il 23/06/2014 23:35, Alexey Kardashevskiy ha scritto:
>> nec-usb-xhci is off for PC_COMPAT_1_3 because of what? PIIX emulation was
>> broken in 1.3? Or nec-usb-xhci?
>
> nec-usb-xhci is not "off".
Yes, my bad, I understood (but explained this wrong) that XHCI is enabled
but without MSI.
>
> .driver = "nec-usb-xhci",\
> .property = "msi",\
> .value = "off",\
>
> What's off is MSI (and MSI-X), because it wasn't implemented.
>
>> If it is the latter, why is the tweak limited by PC?
>
> Because at the time nobody cared about migration compatibility (even now
> only pSeries is starting to care).
"only pSeries"? There are plenty of x86 machines already and if it is not
for migration support, then what are they all for? :)
>> Looks like I must copy PC_COMPAT_X_X as PSERIES_COMPAT_X_X starting 1.6 (or
>> 1.7 - whichever starts supporting migration well enough on pseries) because
>> pretty much of what they do is tweaking PCI devices and we can have all of
>> these devices on pseries.
>
> It's not necessary to do this retroactively, unless you're planning to test
> forward migration from 1.6 to 2.1. Just start with 2.2 (and add
> pseries-2.1 now as an alias).
>
> Note that firmware interfaces and CPU features should also be versioned if
> they're guest visible. That's the point of functions like pc_compat_1_6.
>
>> And then keep an eye on what is happening in PC
>> world to copy same tweaks to pseries as they come. Is that correct?
>
> Yes. We should come up sooner or later with a way to share the tweaks though.
>
>> Others (ARM, s390) do not do that because they do not support PCI? Or
>> migration? Or some other reason?
>
> This is not limited to PCI. Others do not support migration across
> different QEMU versions.
Yeah, I got that now. Thanks!
--
Alexey
- [Qemu-devel] machines and versions - why so many?, Alexey Kardashevskiy, 2014/06/23
- Re: [Qemu-devel] machines and versions - why so many?, Peter Maydell, 2014/06/23
- Re: [Qemu-devel] machines and versions - why so many?, Paolo Bonzini, 2014/06/24
- Re: [Qemu-devel] machines and versions - why so many?,
Alexey Kardashevskiy <=
- Re: [Qemu-devel] machines and versions - why so many?, Markus Armbruster, 2014/06/24
- Re: [Qemu-devel] machines and versions - why so many?, Alexey Kardashevskiy, 2014/06/24
- Re: [Qemu-devel] machines and versions - why so many?, Andreas Färber, 2014/06/24
- Re: [Qemu-devel] machines and versions - why so many?, Alexey Kardashevskiy, 2014/06/24
Re: [Qemu-devel] machines and versions - why so many?, Markus Armbruster, 2014/06/23