Re: [Qemu-devel] [PATCH] -machine vmport=off: Allow disabling of VMWare ioport emulation

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Slutz, Donald Christopher (dslutz@verizon.com) wrote:
> What is happening with this patch?  I would like to use this code.

I need to rework it for the new machine types code; but it was pretty
low down my list of priorities; but I can try and get a minute for it
again.

Dave

> 
>    -Don Slutz
> 
> ________________________________________
> From: qemu-devel-bounces+don=cloudswitch.com@nongnu.org [qemu-devel-bounces+don=cloudswitch.com@nongnu.org] on behalf of Gerd Hoffmann [kraxel@redhat.com]
> Sent: Tuesday, May 20, 2014 6:10 AM
> To: Richard W.M. Jones
> Cc: mst@redhat.com; qemu-devel@nongnu.org; armbru@redhat.com; Dr. David Alan Gilbert; aliguori@amazon.com; Anthony PERARD
> Subject: Re: [Qemu-devel] [PATCH] -machine vmport=off: Allow disabling of VMWare ioport emulation
> 
>   Hi,
> 
> > It was disabled in this patch.  The commit message is saying that
> > vmport cannot work in Xen, but I'm not exactly clear why.
> >
> >   commit 1611977c3d8fdbdac6090cbd1f5555cee4aed6d9
> >   Author: Anthony PERARD <anthony.perard@citrix.com>
> >   Date:   Tue May 3 17:06:54 2011 +0100
> >
> >     pc, Disable vmport initialisation with Xen.
> >
> >     This is because there is not synchronisation of the vcpu register
> >     between Xen and QEMU, so vmport can't work properly.
> 
> Ah, ok.  The backdoor has side effects (writing the port does modify
> vcpu registers).  That is the bit which is problematic for xen.  Scratch
> the idea then.
> 
> Original patch is fine.
> 
> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
> 
> cheers,
>   Gerd
> 
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK