2015-10-19 18:57 GMT+02:00 Stefano Stabellini < stefano.stabell...@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.
