Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755559Ab3DZM7s (ORCPT ); Fri, 26 Apr 2013 08:59:48 -0400 Received: from mail-vc0-f174.google.com ([209.85.220.174]:63789 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755233Ab3DZM7q (ORCPT ); Fri, 26 Apr 2013 08:59:46 -0400 MIME-Version: 1.0 In-Reply-To: <1577576.O1Cm2pf5KD@wuerfel> References: <1366974299-17877-1-git-send-email-pranavkumar@linaro.org> <1577576.O1Cm2pf5KD@wuerfel> Date: Fri, 26 Apr 2013 18:29:45 +0530 Message-ID: Subject: Re: [PATCH 0/2] Early printk support for virtio console devices. From: Anup Patel To: Arnd Bergmann Cc: linaro-kernel@lists.linaro.org, Peter Maydell , patches@linaro.org, "linux-kernel@vger.kernel.org List" , Alexander Graf , 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: 1883 Lines: 45 On 26 April 2013 18:03, Arnd Bergmann wrote: > On Friday 26 April 2013 17:36:16 Anup Patel wrote: >> On 26 April 2013 17:03, Peter Maydell wrote: >> > On 26 April 2013 12:19, Alexander Graf wrote: >> >> MMIO registers are handled by a different layer than the virtio >> >> console itself. After the virtio refactoring in QEMU, they will >> >> be completely separate drivers. >> > >> > Good point -- we don't really want to be mixing up the >> > transport and the backend. You can see it in the kvmtool >> > patch, in fact -- it introduces an "if this is virtio-console" >> > special case into the mmio.c file which previously was >> > entirely backend agnostic. >> >> Well, we can always have virtio device specific config registers >> handle by virtio device backends and generic virtio config register >> handled by transport. >> >> kvmtool patch is hacky because it does not provide virtio device >> specific config read/write callbacks. > > Couldn't kvmtool implement the interface used by smh_printch() > for early output instead? > > Or if that's not a fitting inteface, maybe a psci call for writing > a character to the console? > > Arnd I am curious about how smh-based or hypercall-based early prints would be handled in following scenario: "A board is running KVM ARM enabled kernel and linux console on serial port. Now a user remotely connects to the board via telnet/ssh and launches a VM with smh-based or hypercall-based earlyprintk." In the above scenario, will smh-based or hypercall-based earlyprints appear to user on remote shell or not ? --Anup -- 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/