From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:48585) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ScY8z-00023B-Ao for qemu-devel@nongnu.org; Thu, 07 Jun 2012 04:32:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ScY8t-0007z4-1G for qemu-devel@nongnu.org; Thu, 07 Jun 2012 04:32:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56620) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ScY8s-0007yt-Pp for qemu-devel@nongnu.org; Thu, 07 Jun 2012 04:32:30 -0400 Message-ID: <4FD06725.70905@redhat.com> Date: Thu, 07 Jun 2012 10:32:37 +0200 From: Hans de Goede MIME-Version: 1.0 References: <1338953515.7150.150.camel@pasglop> <4FCEEDC5.7090807@us.ibm.com> <1339017219.7150.170.camel@pasglop> In-Reply-To: <1339017219.7150.170.camel@pasglop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [qemu-devel][RFC] Enable usb with default options List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Benjamin Herrenschmidt Cc: Anthony Liguori , li zhang , qemu-devel@nongnu.org, zhlcindy@linux.vnet.ibm.com Hi, Sorry for jumping in the middle of the thread, I missed the beginning of this. Enabling USB by default, esp. emulating a USB mouse by default is a *bad* idea. They way the periodic schedule of the various USB controllers works means that emulating a USB device means a 1000 vm exits per second extra, even when the vm is completely idle! USB powermanagement can be used to negate this, but this is off in both Linux and Windows for HID devices by default because there are too many broken HID devices. Regards, Hans