From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fabio Fantoni Subject: Re: [Qemu-devel] Question about xen disk unplug support for ahci missed in qemu Date: Mon, 19 Oct 2015 20:29:19 +0200 Message-ID: References: <561D2966.9070007@m2r.biz> <561D3513.8060005@redhat.com> <562160CC.8050204@redhat.com> <1445254058.13733.39.camel@redhat.com> <56252046.7070508@redhat.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6878354288384402454==" Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Stefano Stabellini Cc: Anthony PERARD , "qemu-devel@nongnu.org" , John Snow , Gerd Hoffmann , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org --===============6878354288384402454== Content-Type: multipart/alternative; boundary=047d7b33ca86cf34f805227952b6 --047d7b33ca86cf34f805227952b6 Content-Type: text/plain; charset=UTF-8 2015-10-19 18:57 GMT+02:00 Stefano Stabellini < stefano.stabellini@eu.citrix.com>: > On Mon, 19 Oct 2015, John Snow wrote: > > On 10/19/2015 07:44 AM, Stefano Stabellini wrote: > > > 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. > > > > > > > OVMF and AHCI go hand in hand here from my viewpoint. I'm happy to debug > > any OVMF+SATA/AHCI problems that are reported. > > > > Last I saw, Laszlo asked Fabio for some more information on this > > problem, so I am waiting for that information to start work on that > issue. > > Fabio reported a bug using OVFM+xen_disk, no AHCI involved. OVFM has > already support for the Xen PV disk protocol, see > OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.c. > I not tried with ahci in ovmf in latest because as you told that is a missing unplug case in qemu. I tried with xendisk and ide, the empty cdrom problem is with both, from xl domU cfg: ',raw,xvdb,ro,cdrom' for xendisk and ',raw,hdb,ro,cdrom' for ide. Using seabios instead boot correctly, with ovmf not: http://lists.xen.org/archives/html/xen-devel/2015-10/msg01833.html If I remember good also in latest test persist also the problem that ovmf not respect the boot order parameter. --047d7b33ca86cf34f805227952b6 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
2015-10-19 18:57 GMT+02:00 Stefano Stabellini <stefano.stabellini@eu.citrix.com>:
On Mon, 19 Oct 2015, John Snow= wrote:
> On 10/19/2015 07:44 AM, Stefano Stabellini wrote:
> > On Mon, 19 Oct 2015, Gerd Hoffmann wrote:
> >>=C2=A0 =C2=A0Hi,
> >>
> >>>> I'm trying to follow this discussion as best as I= am able, but my lack
> >>>> of experience with Xen prevents me from really partic= ipating in a
> >>>> meaningful way.
> >>>>
> >>>> (I see that Laszlo is still discussing some CD-ROM is= sues with Fabio
> >>>> which may be of interest to me...)
> >>>>
> >>>> At any rate, I won't be authoring any Xen-specifi= c 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, w= e'll need to discuss further,
> >>>> preferably over some RFC patches.
> >>>
> >>> That's fine. AHCI hot-plugging would go a long way an= d 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 l= ike this:
> >>
> >>=C2=A0 =C2=A0(1) boot disk is hooked up using both xenbus and = ide.
> >>=C2=A0 =C2=A0(2) seabios boots using ide.
> >>=C2=A0 =C2=A0(3) linux kernel activates xenbus, at which point= qemu zaps the ide
> >>=C2=A0 =C2=A0 =C2=A0 =C2=A0disks to avoid the disk being prese= nt twice in the system.
> >>
> >> Correct?
> >>
> >> Do we really want repeat this exercise for AHCI?=C2=A0 Alot h= as 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 worki= ng on
> > OVMF instead and fix the bug about empty cdrom drives reported by= Fabio.
> >
>
> OVMF and AHCI go hand in hand here from my viewpoint. I'm happy to= debug
> any OVMF+SATA/AHCI problems that are reported.
>
> Last I saw, Laszlo asked Fabio for some more information on this
> problem, so I am waiting for that information to start work on that is= sue.

Fabio reported a bug using OVFM+xen_disk, no AHCI involved. OVF= M has
already support for the Xen PV disk protocol, see
OvmfPkg/XenPvBlkDxe/XenPvBlkDxe.c.

I no= t tried with ahci in ovmf in latest because as you told that is a missing u= nplug case in qemu.

I tried with xendisk and ide, the emp= ty cdrom problem is with both, from xl domU cfg:
',raw,xvdb,ro,cdrom' for xendisk and ',raw,hdb,ro,cdrom'=
 for ide.
Using seabios instead boot cor=
rectly, with ovmf not:
http://lists.xen.org/archives/html/xen-devel/=
2015-10/msg01833.html

If I remem=
ber good also in latest test persist also the problem that ovmf not respect=
 the boot order parameter.
=C2=A0

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