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From: Gerd Hoffmann <kraxel@redhat.com>
To: "Richard W.M. Jones" <rjones@redhat.com>
Cc: mst@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	aliguori@amazon.com, Anthony PERARD <anthony.perard@citrix.com>
Subject: Re: [Qemu-devel] [PATCH] -machine vmport=off: Allow disabling of VMWare ioport emulation
Date: Tue, 20 May 2014 12:10:41 +0200	[thread overview]
Message-ID: <1400580641.29693.8.camel@nilsson.home.kraxel.org> (raw)
In-Reply-To: <20140520091802.GP1302@redhat.com>

  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

  reply	other threads:[~2014-05-20 10:17 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-19 17:00 [Qemu-devel] [PATCH] -machine vmport=off: Allow disabling of VMWare ioport emulation Dr. David Alan Gilbert (git)
2014-05-19 17:03 ` Richard W.M. Jones
2014-05-20  7:40 ` Gerd Hoffmann
2014-05-20  8:47   ` Dr. David Alan Gilbert
2014-05-20  9:18     ` Richard W.M. Jones
2014-05-20 10:10       ` Gerd Hoffmann [this message]
2014-09-25 13:40         ` Slutz, Donald Christopher
2014-09-25 15:07           ` Dr. David Alan Gilbert
2014-09-25 17:47             ` Slutz, Donald Christopher
2014-09-25 18:00               ` Dr. David Alan Gilbert

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