Re: [Xen-devel] [PATCH v2][RFC] libxl: Add AHCI support for upstream qemu

[Fabio Fantoni <fabio.fantoni@xxxxxxx>]

Il 19/05/2015 14:13, Fabio Fantoni ha scritto:
> Il 19/05/2015 12:40, Wei Liu ha scritto:
> > On Mon, May 18, 2015 at 07:22:01PM +0200, Fabio Fantoni wrote:
> > > Il 18/05/2015 17:53, Wei Liu ha scritto:
> > > > On Thu, May 14, 2015 at 01:11:13PM +0200, Fabio Fantoni wrote:
> > > > > Usage:
> > > > > ahci=0|1 (default=0)
> > > > >
> > > > > If enabled adds ich9 disk controller in ahci mode and uses it with
> > > > > upstream qemu to emulate disks instead of ide.
> > > > Is ICH9 available in our default setup?
> > > >
> > > > Why do we not always enable AHCI?
> > > ahci seems require ich9 controller (default in q35 but not in older 
> > > used by
> > > xen), I think that change it ide->ahci automatically for all cases may
> > > causes problems, probably in save/restore and more probably in 
> > > windows <=7
> > > without pv where change ide<->ahci require a registry change for not 
> > > have
> > > blue screen.
> > I guess we now have a QEMU with Q35. But migrating from previous
> > previous versions will indeed need to be taken care of.
> This patch don't add q35 cipset support but only ich9 ahci disk 
> controller in older and only cipset supported in xen.
> Time ago I tried to add q35 support in xen but I had some problems I 
> was unable to solves and nobody helped me.
> Q35 have newer ich9 ahci disk controller as default, on older cipset 
> must be added (done in this patch).
> qemu, kvm ovmf already support q35, xen need changes at least in 
> hvmloader (that I'm probably unable to do) and libxl (that I started 
> time ago without good result), Add ahci support and switch all qemu 
> parameters in libxl to new -device is a good start also for future q35 
> support (are both part needed based on my old q35 tests on xen)
> > > > > It doesn't support cdroms which still use ide (cdroms will use 
> > > > > "-device
> > > > > ide-cd" as new qemu parameters)
> > > > > Ahci requires new qemu parameters but for now other emulated disks 
> > > > > cases
> > > > > remains with old ones because automatic bus selection seems bugged in
> > > > > qemu using new parameters. (I'll retry)
> > > > Buggy as in? Have you reported to QEMU upstream?
> > > Already reported long time ago in xen-devel and qemu-devel, the only 
> > > reply
> > > from qemu-devel was to use fixed bus and is what I did in v2 of this 
> > > patch.
> > > Can someone tell me if can be a problem fixed bus?
> > I don't have enough knowledge on this. Maybe Anthony and Stefano have
> > more insight.
> >
> > Wei.
Ping...
Any review and/or comment about AHCI support patch is appreciated.

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