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

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

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.

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Ian.


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