From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Qemu-devel] Questions regarding ivshmem spec Date: Thu, 25 Aug 2011 17:00:14 +0300 Message-ID: <4E56556E.1080805@redhat.com> References: <1314278954.3692.55.camel@lappy> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: cam , David Evensky , Pekka Enberg , qemu-devel , kvm To: Sasha Levin Return-path: Received: from mx1.redhat.com ([209.132.183.28]:6816 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750846Ab1HYOAi (ORCPT ); Thu, 25 Aug 2011 10:00:38 -0400 In-Reply-To: <1314278954.3692.55.camel@lappy> Sender: kvm-owner@vger.kernel.org List-ID: On 08/25/2011 04:29 PM, Sasha Levin wrote: > 2. The spec describes DOORBELL as an array of DWORDs, when one guest > wants to poke a different guest it would write something into the offset > of the other guest in the DOORBELL array. > Looking at the implementation in QEMU, DOORBELL is one DWORD, when > writing to it the upper WORD is the guest id and the lower WORD is the > value. > What am I missing here? > The spec in qemu.git is accurate. The intent is to use an ioeventfd bound into an irqfd so a write into the doorbell injects an interrupt directly into the other guest, without going through qemu^Wkvm tool. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:53793) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QwaU6-00011B-P7 for qemu-devel@nongnu.org; Thu, 25 Aug 2011 10:00:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QwaU2-0005G7-4y for qemu-devel@nongnu.org; Thu, 25 Aug 2011 10:00:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:17378) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QwaU1-0005Fz-SA for qemu-devel@nongnu.org; Thu, 25 Aug 2011 10:00:38 -0400 Message-ID: <4E56556E.1080805@redhat.com> Date: Thu, 25 Aug 2011 17:00:14 +0300 From: Avi Kivity MIME-Version: 1.0 References: <1314278954.3692.55.camel@lappy> In-Reply-To: <1314278954.3692.55.camel@lappy> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Questions regarding ivshmem spec List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Sasha Levin Cc: Pekka Enberg , cam , qemu-devel , David Evensky , kvm On 08/25/2011 04:29 PM, Sasha Levin wrote: > 2. The spec describes DOORBELL as an array of DWORDs, when one guest > wants to poke a different guest it would write something into the offset > of the other guest in the DOORBELL array. > Looking at the implementation in QEMU, DOORBELL is one DWORD, when > writing to it the upper WORD is the guest id and the lower WORD is the > value. > What am I missing here? > The spec in qemu.git is accurate. The intent is to use an ioeventfd bound into an irqfd so a write into the doorbell injects an interrupt directly into the other guest, without going through qemu^Wkvm tool. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.