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Re: [Qemu-devel] Question about xen disk unplug support for ahci missed
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu |
Date: |
Mon, 19 Oct 2015 12:44:01 +0100 |
User-agent: |
Alpine 2.02 (DEB 1266 2009-07-14) |
On Mon, 19 Oct 2015, Gerd Hoffmann wrote:
> Hi,
>
> > > I'm trying to follow this discussion as best as I am able, but my lack
> > > of experience with Xen prevents me from really participating in a
> > > meaningful way.
> > >
> > > (I see that Laszlo is still discussing some CD-ROM issues with Fabio
> > > which may be of interest to me...)
> > >
> > > At any rate, I won't be authoring any Xen-specific hacks to the AHCI
> > > device, but I do have plans to implement hot-plugging emulation as per
> > > the AHCI spec. Perhaps this is sufficient for the Xen layer, but someone
> > > else will need to author the appropriate glue code.
> > >
> > > If "real" hot-plugging is not sufficient, we'll need to discuss further,
> > > preferably over some RFC patches.
> >
> > That's fine. AHCI hot-plugging would go a long way and once we have
> > that, the rest is easy.
>
> Can we get some more background on this?
>
> IIRC the IDE bits are needed to boot hvm guests, which goes like this:
>
> (1) boot disk is hooked up using both xenbus and ide.
> (2) seabios boots using ide.
> (3) linux kernel activates xenbus, at which point qemu zaps the ide
> disks to avoid the disk being present twice in the system.
>
> Correct?
>
> Do we really want repeat this exercise for AHCI? Alot has changed since
> this boot hack for ide was added ...
>
> As far I know OVMF has xenbus drivers, so OVMF should already boot xen
> guests just fine without this, correct?
I agree with you that the current unplug in nasty. Also I don't care
much about AHCI, in fact I don't think we should be spending efforts
into making that scenario work better. I think we should be working on
OVMF instead and fix the bug about empty cdrom drives reported by Fabio.
> Can we just have xenbus drivers for seabios too? seabios can run disk
> drivers in 32bit mode meanwhile, so this should not be as difficult any
> more as it used to be.
Sure, I would be happy to see that happen, but I won't be working on it.
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, (continued)
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Kevin Wolf, 2015/10/16
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Paul Durrant, 2015/10/16
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Kevin Wolf, 2015/10/16
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Paul Durrant, 2015/10/16
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Kevin Wolf, 2015/10/16
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Fabio Fantoni, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Eric Blake, 2015/10/16
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, John Snow, 2015/10/16
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Stefano Stabellini, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Gerd Hoffmann, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu,
Stefano Stabellini <=
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, John Snow, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Stefano Stabellini, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Fabio Fantoni, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Laszlo Ersek, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Fabio Fantoni, 2015/10/19
- Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu, Stefano Stabellini, 2015/10/19