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Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug.
From: |
Jason Baron |
Subject: |
Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug. |
Date: |
Fri, 12 Oct 2012 11:00:08 -0400 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Fri, Oct 12, 2012 at 12:06:44PM +0200, Gerd Hoffmann wrote:
> Hi,
>
> >>> I just tried out getting rid of the bridges by default.
> >>
> >> That clearly raises the question which devices should be created
> >> automatically by -M q35. I think the devices which are part of the ich9
> >> chipset should be there by default. /me looks at my laptop which
> >> happens to have a ich9 chipset.
> >
> > The reason this is a bad idea is very simple: we only have a way to add
> > devices not to remove them. So if you miss a device which your guest
> > needs, it is easy to add, but there is no way to remove.
>
> Why would you want remove devices? They don't harm when present. And
> you can't remove them on real hardware either. Try ordering a ich9
> without sound or usb ;)
>
> >> Real ich9 has the e1000 @ 00:19.0, so it would make sense to place one
> >> there. Adding a default nic will probably create some headache though,
> >> so maybe better don't.
> >
> > And that's just one example.
>
> It is problematic because the nic needs configuration and configuring a
> builtin device is tricky. Also our e1000 model isn't the ich9 one.
>
> Most other chipset devices are not problematic at all as they are just
> controllers where you can attach stuff to (and by default there isn't
> anything attached). This includes:
>
> * pcie ports (waiting for pcie devices plugged in).
> * ahci controller (waiting for disks/cdroms being attached).
> * intel-hda (waiting for audio coded (hda-*) being attached).
> * ehci+uhci (waiting for usb devices being plugged in).
>
> The stuff being attached/plugged there needs configuration, but not the
> controllers themself.
>
> > Fact is, we don't emulate real hardware exactly.
>
> But we try to.
>
> > So let's have a minimal machine and if you want to add e1000 audio etc,
> > you can do this. We can even teach management to do it with friendly
> > UI as opposed to cryptic machine types.
>
> /me disagrees.
>
What if we have a 'basic' configuration as Michael suggests, but have an
easy way to specify that we want these additional built-in
controllers/bridges at their default slot.
For example, for q35 I can currently pass '-usb' and it will create a
uhci at slot 1d func 0. (I have small patch to add ehci as well).
Not sure if we have appropriate options we can piggy-back on for default
sound and bridges, but we can add these later, if this makese sense.
Thanks,
-Jason
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., (continued)
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Jason Baron, 2012/10/11
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Michael S. Tsirkin, 2012/10/11
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Jason Baron, 2012/10/12
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Michael S. Tsirkin, 2012/10/13
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Gerd Hoffmann, 2012/10/12
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Michael S. Tsirkin, 2012/10/12
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Gerd Hoffmann, 2012/10/12
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug., Michael S. Tsirkin, 2012/10/12
- Re: [Qemu-devel] [PATCH v2 21/21] q35: add acpi-based pci hotplug.,
Jason Baron <=
[Qemu-devel] [PATCH v2 13/21] q35: Re-base q35, Jason Baron, 2012/10/08