From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759850AbZD1LGT (ORCPT ); Tue, 28 Apr 2009 07:06:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756097AbZD1LGC (ORCPT ); Tue, 28 Apr 2009 07:06:02 -0400 Received: from mx2.redhat.com ([66.187.237.31]:41271 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754369AbZD1LGA (ORCPT ); Tue, 28 Apr 2009 07:06:00 -0400 Message-ID: <49F6E313.7020502@redhat.com> Date: Tue, 28 Apr 2009 14:05:55 +0300 From: Avi Kivity User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Gregory Haskins CC: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, davidel@xmailserver.org Subject: Re: [KVM PATCH v2 2/2] kvm: add support for irqfd via eventfd-notification interface References: <20090424042142.1796.60756.stgit@dev.haskins.net> <20090424042518.1796.65593.stgit@dev.haskins.net> <49F572EF.4010909@redhat.com> <49F58A8C.7090808@novell.com> <49F58D75.7040304@redhat.com> <49F5B2DA.5060207@novell.com> <49F6CDFC.6000400@redhat.com> <49F6DB9D.3080501@novell.com> <49F6E1CA.1010106@redhat.com> <49F6E2BB.9070604@novell.com> In-Reply-To: <49F6E2BB.9070604@novell.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Gregory Haskins wrote: >>>> But eventfd_signal basically marries us to eventfd. >>>> >>>> >>> Well, only if we expect the fd to have eventfd semantics. There are >>> advantages to doing so, as we have discussed, because things like AIO >>> can polymorhpically signal an interrupt without even knowing whats >>> behind the eventfd. But this isn't a strict requirement to support >>> AIO. Really all we need is a way for both kernel and userspace to >>> signal. Perhaps I should export an "irqfd_signal()" function from kvm, >>> which today will map to eventfd_signal(), and tomorrow to ??. I don't >>> think using f_ops->write() is an option for in-kernel signaling, so we >>> need some kind of interface here. >>> >>> Does that sound reasonable? >>> >>> >> irqfd_signal() ties the user of irqfd to kvm. I want this user to be >> independent of kvm; it should work with eventfd, kvm's eventfd >> lookalike (if we move away from eventfd) or pipes. >> > > So what is your proposal for such interface? > > ->write(). -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.