Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757594Ab3DSJZh (ORCPT ); Fri, 19 Apr 2013 05:25:37 -0400 Received: from mail-pd0-f179.google.com ([209.85.192.179]:62966 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757030Ab3DSJZg (ORCPT ); Fri, 19 Apr 2013 05:25:36 -0400 MIME-Version: 1.0 In-Reply-To: <20130419090558.GA13283@mudshark.cambridge.arm.com> References: <1366264344-28025-1-git-send-email-pranavkumar@linaro.org> <20130419090558.GA13283@mudshark.cambridge.arm.com> Date: Fri, 19 Apr 2013 14:55:35 +0530 Message-ID: Subject: Re: [RFC] arm64: Early printk support for virtio-mmio console devices. From: Pranavkumar Sawargaonkar To: Will Deacon Cc: Marc Zyngier , "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: 1381 Lines: 34 Hi Will, On 19 April 2013 14:35, Will Deacon wrote: > Hello, > > On Thu, Apr 18, 2013 at 09:48:49AM +0100, Pranavkumar Sawargaonkar wrote: >> Actually i thought adding a config register will be easier to add a >> code than writing entire emulation as 8250 emulation will require to >> deal with dealing with more registers and more code. > > kvmtool already has an 8250 emulation! All we need to do is hack together > something which will allow us to instantiate those ioport devices in a more > flexible manner (namely, inside the MMIO space for ARM). For earlyprintk, I > suspect we can get away without an interrupt too, which should simplify > things a bit to start with. > > Regardless of the outcome of this discussion, I think getting the 8250 > working on ARM is definitely something worth doing. If I get time, I'll take > a look. I am not against using 8250 emulation (as far as it solves printk issues for kernel booting logs), but my point is why not to add early read-write support for virtio console, which also can be useful in emulation less mach-virt environment also ? Thanks, Pranav > > Will -- 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/