Re: [Xen-devel] [PATCH v4] libxl: Add AHCI support for upstream qemu

[Fabio Fantoni <fabio.fantoni@xxxxxxx>]

Il 09/07/2015 12:26, Ian Campbell ha scritto:
> On Wed, 2015-07-08 at 16:31 +0200, Fabio Fantoni wrote:
> > Usage:
> > hdtype=ide|ahci (default=ide)
> >
> > If hdtype=ahci adds ich9 disk controller in ahci mode and uses it with
> > upstream qemu to emulate disks instead of ide.
> > It doesn't support cdroms which still using ide (cdroms will use
> > "-device ide-cd" as new qemu parameter)
> > Ahci requires new qemu parameter but for now other emulated disks cases
> > remains with old ones (I did it in other patch, not needed by this one)
> > I did it as libxl parameter disabled by default to avoid possible
> > problems:
> > - with save/restore/migration (restoring with ahci a domU that was with
> > ide instead)
> > - windows < 8 without pv drivers (a registry key change is needed for
> > AHCI<->IDE change FWIK to avoid possible blue screen)
> > - windows XP or older that many not support ahci by default.
> > Setting AHCI with libxl parameter and default to disabled seems the best
> > solution.
> > AHCI increase hvm domUs boot performance. On linux hvm domU I saw up to
> > only 20% of the previous total boot time, whereas boot time decrease a
> > lot on W7 domUs for most of boots I have done. Small difference in boot
> > time compared to ide mode on W8 and newer (probably other xen
> > improvements or fixes are needed not ahci related)
> >
> > Signed-off-by: Fabio Fantoni <fabio.fantoni@xxxxxxx>
> >
> > ---
> >
> > Changes in v4:
> > - libxl.h: LIBXL_HAVE_AHCI->LIBXL_HAVE_HVM_AHCI
> In retrospect this should have been LIBXL_HAVE_HVM_HDTYPE. Since the
> above was my suggestion if you agree I can make that simple change as I
> commit.
Yes you can change it directly as this change not risk introduce bug, 
thanks.
Is also Stabellini Acked-by (he did in v2) needed for qemu parameters 
part (not changed in v3 and v4)?
http://lists.xen.org/archives/html/xen-devel/2015-06/msg03551.html
I not added in latest posted version because I don't know if can be 
still valid.
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
>
> Ian.

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