From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57116) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wmh7J-0000DN-Lb for qemu-devel@nongnu.org; Tue, 20 May 2014 06:17:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wmh7C-0004Xl-PX for qemu-devel@nongnu.org; Tue, 20 May 2014 06:17:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25421) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wmh7C-0004Xg-HG for qemu-devel@nongnu.org; Tue, 20 May 2014 06:17:46 -0400 Message-ID: <1400580641.29693.8.camel@nilsson.home.kraxel.org> From: Gerd Hoffmann Date: Tue, 20 May 2014 12:10:41 +0200 In-Reply-To: <20140520091802.GP1302@redhat.com> References: <1400518826-19144-1-git-send-email-dgilbert@redhat.com> <1400571640.10626.7.camel@nilsson.home.kraxel.org> <20140520084725.GA2538@work-vm> <20140520091802.GP1302@redhat.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] -machine vmport=off: Allow disabling of VMWare ioport emulation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 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 > 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 cheers, Gerd