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

[Ian Campbell <ian.campbell@citrix.com>]

On Thu, 2015-07-09 at 12:36 +0200, Fabio Fantoni wrote:
> 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@m2r.biz>
> >>
> >> ---
> >>
> >> 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.

Done, pod doc fixed and applied, thanks.

Ian.