From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] ioeventfd: Introduce KVM_IOEVENTFD_FLAG_PIPE Date: Mon, 04 Jul 2011 17:59:12 +0300 Message-ID: <4E11D540.6020003@redhat.com> References: <1309712689-4290-1-git-send-email-levinsasha928@gmail.com> <4E10A3E6.1070606@redhat.com> <1309715091.4117.16.camel@sasha> <4E1195A1.10103@redhat.com> <1309790307.4117.25.camel@sasha> <4E11D20F.9020509@redhat.com> <1309791134.4117.27.camel@sasha> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Ingo Molnar , Marcelo Tosatti , "Michael S. Tsirkin" , Pekka Enberg To: Sasha Levin Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35252 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755882Ab1GDO7a (ORCPT ); Mon, 4 Jul 2011 10:59:30 -0400 In-Reply-To: <1309791134.4117.27.camel@sasha> Sender: kvm-owner@vger.kernel.org List-ID: On 07/04/2011 05:52 PM, Sasha Levin wrote: > > > > I can't really see that as useful. eventfds destroy information; > > without datamatch, you have no idea what value was written. Even with > > datamatch, you have no idea how many times it was written. With a > > range, you also have no idea which address was written. It's pretty > > meaningless. > > > > It is pretty useless, but I didn't want the ioctl to behave differently > when passing a socket or an eventfd. > > If we do go for a new ioctl as you suggested then yes, problem solved. > Yes. I guess it depends on the numbers of if () s introduced into the code. If it starts to feel dirty, split it into a separate ioctl (they can both call common helpers). It's fine to allow size > 8 for eventfds. Yes it's meaningless, but it's not harmful and I can't see it breaking anything. Note that we may need to change the way we do matches - currently 'size' means the access size, with an exact match on the address, but the new meaning is 'any address from start to start+size-1'. -- error compiling committee.c: too many arguments to function