From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:36218) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TTgLX-0007ud-Mi for qemu-devel@nongnu.org; Wed, 31 Oct 2012 18:01:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TTgLW-0005B5-0i for qemu-devel@nongnu.org; Wed, 31 Oct 2012 18:01:11 -0400 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:38110) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TTgLV-000585-CT for qemu-devel@nongnu.org; Wed, 31 Oct 2012 18:01:09 -0400 Received: from /spool/local by e28smtp09.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 1 Nov 2012 03:30:49 +0530 Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q9VM0iiC35127416 for ; Thu, 1 Nov 2012 03:30:45 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id qA13UaKW019746 for ; Thu, 1 Nov 2012 14:30:36 +1100 From: Anthony Liguori Date: Wed, 31 Oct 2012 17:00:26 -0500 Message-Id: <1351720834-22805-1-git-send-email-aliguori@us.ibm.com> Subject: [Qemu-devel] [PATCH 0/8] add paravirtualization hwrng support (v3) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Amit Shah , Paolo Bonzini , Andreas Faerber , "H. Peter Anvin" Hi, This series implements the backend and frontend infrastructure for virtio-rng. This is similar to previous series sent out by both Amit and myself although it has been trimmed down considerably. In terms of backends, a file and EGD backend are supported. The file defaults to /dev/random based on the feedback from Peter. It's still possible to support /dev/urandom though as an entropy source by overriding the file name. v1 -> v2: - Include default backend patch from separate series - Add a rate limiting patch v2 -> v3: - Small bug fix spotted by Paolo My take away from all of the various discussions on what the Right Way to use virtio-rng is: 1) /dev/random should always be used as the entropy source (I've left it configurable though) 2) I think the Right Way to configure virtio-rng is to figure out what the available entropy is on the host, and then decide how to allocate that to each guest. As such, I've implemented rate limiting. I think QEMU is the right place to do this because this is a property of specific virtual machines. I can imagine a cloud provider wanting to guarantee a certain level of entropy for different classes of VMs. Even if rngd could be used to do this, configuring it differently for different guests would be cumbersome. 3) `qemu -device virtio-rng-pci` will Just Work but risks exhausting host entropy. This means we can't make it the default for machines. But for most command line users, I think this is the behavior they want.