From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754544Ab0CCQmy (ORCPT ); Wed, 3 Mar 2010 11:42:54 -0500 Received: from mail2.microsoft.com ([131.107.115.215]:58025 "EHLO smtp.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754448Ab0CCQmx convert rfc822-to-8bit (ORCPT ); Wed, 3 Mar 2010 11:42:53 -0500 From: Hank Janssen To: "'linux-kernel@vger.kernel.org'" , "devel@driverdev.osuosl.org" , "virtualization@lists.osdl.org" CC: Haiyang Zhang , Hashir Abdi Subject: Ringbuffer usage in Linux Hyper-V drivers Thread-Topic: Ringbuffer usage in Linux Hyper-V drivers Thread-Index: AQHKuvCGLAH71qxVt0GYupGkI8PEwA== Date: Wed, 3 Mar 2010 16:42:27 +0000 Message-ID: <8AFC7968D54FB448A30D8F38F259C56212EE39C0@TK5EX14MBXC116.redmond.corp.microsoft.com> References: <1FB5E1D5CA062146B38059374562DF725A908A11@TK5EX14MBXC126.redmond.corp.microsoft.com> <20100217235223.GG12197@kroah.com> In-Reply-To: <20100217235223.GG12197@kroah.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org All, I have been looking at one of the TODO items in the Linux Hyper-V drivers. Specifically the one that says; - remove RingBuffer.c to use in-kernel ringbuffer functions instead. I spend some time figuring out the ring buffer capability inside of the Linux Kernel to see if we could change the Hyper-V ring buffer out for the in-kernel ring buffer capability. The ring buffer in the Hyper-V Linux drivers is used to communicate with the parent partition running Server 2008 Hyper-V. The ring buffer functionality on the Hyper-V Linux drivers is written to be functionally compatible with" the ring buffer functionality on the Hyper-V Server. Consequently, it is not possible to make any changes that might break the compatibility with server side ring buffer implementation. There is a pretty good chance that ring buffer on Hyper-V will change to support additional functionality. I did further investigations to check on other virtualization technologies. And this same things seems to be true for XEN, they also implemented their own ring buffer implementation on the guest side because of their host side implementation. So my question is to the community at large, am I missing something that would enable me to use an existing ring buffer functionality somehow in the kernel? If not, I want to remove the line from the TODO file that is requesting to use the in-kernel ring buffer functionality. Finally, while checking this out, I looked at a bunch of non virtualization device drivers currently in the kernel. And all the ones I looked at have implemented their own ring buffer. Is there a reason why this might be the case? As usual, any help is appreciated. Thanks, Hank Janssen.