Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936356Ab3DRS7h (ORCPT ); Thu, 18 Apr 2013 14:59:37 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:61896 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752222Ab3DRS7g (ORCPT ); Thu, 18 Apr 2013 14:59:36 -0400 MIME-Version: 1.0 In-Reply-To: <217a4f2dd017af16204391012751e9f9@localhost> References: <1366264344-28025-1-git-send-email-pranavkumar@linaro.org> <51701084.5050706@codeaurora.org> <217a4f2dd017af16204391012751e9f9@localhost> Date: Fri, 19 Apr 2013 00:29:35 +0530 Message-ID: Subject: Re: [RFC] arm64: Early printk support for virtio-mmio console devices. From: Pranavkumar Sawargaonkar To: Marc Zyngier Cc: Christopher Covington , "linaro-kernel@lists.linaro.org" , Anup Patel , Patch Tracking , Rusty Russell , "linux-kernel@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1393 Lines: 37 On 18 April 2013 21:29, Marc Zyngier wrote: > On Thu, 18 Apr 2013 11:25:56 -0400, Christopher Covington > wrote: >> Hi Pranavkumar, >> >> On 04/18/2013 01:52 AM, PranavkumarSawargaonkar wrote: >>> From: Pranavkumar Sawargaonkar >>> >>> This patch implements early printk support for virtio-mmio console >>> devices >>> without using any hypercalls. >> >> Is it possible that using DCC might be an easier solution? > > You would end up with the exact same problem as with a hypercall based > solution: once you're in the hypervisor, what do you do with the data? You > end up having to invent another channel to forward it down to your platform > emulation in order to have it printed where the user expects it. > > Using a MMIO based solution is probably the best solution, as it uses the > existing infrastructure. Completely agree with Marc that instead of writing hypercalls (which will have hypervisor and arch specific implementation) use of existing MMIO and virtio console layer is easier and good option. - Pranav > > M. > -- > Fast, cheap, reliable. Pick two. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/