From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70B7CC04AA6 for ; Mon, 29 Apr 2019 20:02:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3630D2075E for ; Mon, 29 Apr 2019 20:02:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=sifive.com header.i=@sifive.com header.b="XRN9VSnX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729384AbfD2UCY (ORCPT ); Mon, 29 Apr 2019 16:02:24 -0400 Received: from mail-it1-f194.google.com ([209.85.166.194]:50507 "EHLO mail-it1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729185AbfD2UCX (ORCPT ); Mon, 29 Apr 2019 16:02:23 -0400 Received: by mail-it1-f194.google.com with SMTP id q14so1057145itk.0 for ; Mon, 29 Apr 2019 13:02:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=d5+AR4ZQ6S8Je85I3GXhGfH5pQCSFdPGrCwlud052ps=; b=XRN9VSnXHB9YOZLhHV+j78/FmX9TQONi+10x6wv8ySgEM5Q3gC4vGptmW/bxkiWCCY rbcj40eh19ktqbvfBBaI7hdAi4X7nV/L6e/YdSS+D+EnzRxv2YhH95gH9aH/gutPNhO4 RJsx+Ng3drdHuugTlgCMR2KJLCwrOUInFIlaTNKgT+fEPSEflUTe81/58oCezp2WB53J Tdx9M6r9uvjF5dJT3y8Nur7B6mBnp1vd2obduvs8Sw5WW76/Khxa+GnxKWThbOxThEYI WW9SEpLLQwn3CoVL/FBE6o4G0S4hGvPjxIUy76C2Ys9mrLSEiwClLRCuBLFDnHirvptg mgMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=d5+AR4ZQ6S8Je85I3GXhGfH5pQCSFdPGrCwlud052ps=; b=GL9eLAEMGqIC6c8vXFUXNLvsQzsGDt4DUOHkJD5ln45d9w4CCBRCAQpiK5wONv4kb+ Km0azecp4+8Pql5S9qYNcDpqou0jg5GO4TGgbQejN2JN3xaDwBzCHvF6yvbmU8DLqAaT UPe4X3S2joJ1eWuVot54ueqBYCmnVhWc9Sm+yURxtHlzu/100aCr2RJhq2ZTRaj+fJdw ouILfLkXqoRmZSHW9IOtPYxM4lzR5pyjx/aN7msLrTY/frjBs1maKG6u7tNhME9bvQV0 HvgepgAmqw6pOO6p7Cc5boqH99RtX5/ywKx5zXebr1eYx62NUZN6amzb6oXShi5jlLK9 HHXw== X-Gm-Message-State: APjAAAW9NS1A6dCzFl+eMB5gxQgRi7d8GwOltpQmLfyPyDfXGCsW4FvG 3W/8fseVyr/yqkQveaASN9mfCg== X-Google-Smtp-Source: APXvYqw118+txrOO593MhkfuosJ78cNcNeAwZ0b8WAls8UIMDjjD/RyZt63kf1zMwrwLeq+0e7uoZQ== X-Received: by 2002:a24:1f06:: with SMTP id d6mr645397itd.11.1556568142581; Mon, 29 Apr 2019 13:02:22 -0700 (PDT) Received: from localhost (c-73-95-159-87.hsd1.co.comcast.net. [73.95.159.87]) by smtp.gmail.com with ESMTPSA id v25sm7723994ioh.41.2019.04.29.13.02.21 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 29 Apr 2019 13:02:21 -0700 (PDT) Date: Mon, 29 Apr 2019 13:02:21 -0700 (PDT) From: Paul Walmsley X-X-Sender: paulw@viisi.sifive.com To: Anup Patel cc: Christoph Hellwig , Palmer Dabbelt , Greg Kroah-Hartman , Anup Patel , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Atish Patra , Albert Ou , Jiri Slaby , "linux-riscv@lists.infradead.org" Subject: Re: [PATCH] tty: Don't force RISCV SBI console as preferred console In-Reply-To: Message-ID: References: <20190425133435.56065-1-anup.patel@wdc.com> <9a8be7ef-e62e-2a93-9170-e3dc70dfb25f@wdc.com> <20190426062133.GA28529@infradead.org> User-Agent: Alpine 2.21.9999 (DEB 301 2018-08-15) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 26 Apr 2019, Anup Patel wrote: > On Fri, Apr 26, 2019 at 11:51 AM Christoph Hellwig wrote: > > > > On Thu, Apr 25, 2019 at 09:41:21PM -0700, Atish Patra wrote: > > > Do we even need HVC_SBI console to be enabled by default? Disabling > > > CONFIG_HVC_RISCV_SBI seems to be fine while running in QEMU. > > > > > > If we don't need it, I suggest we should remove the config option from > > > defconfig in addition to this patch. > > > > I think the whole concept of the SBI console is a little dangerous. > > It means that for one piece of physical hardware (usually the uart) > > we have two entiries (the M-mode firmware and the OS) in control, > > which tends to rarely end well. > > I think the SBI console is only useful for early SOC bringup and early > SOC debugging when most drivers are not available in upstream > kernel. It cannot (and should not) be used in production deployments. Usually the primary use-case for an abstract console interface is for desktop and server users. Usually Linux distributions want a hardware platform-specific bootloader or BIOS to specify and control the console. Originally I suspect this was implemented in the SBI for semi-hosting purposes, but that's no longer really applicable. - Paul From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50C19C43219 for ; Mon, 29 Apr 2019 20:02:29 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1F67E2075E for ; Mon, 29 Apr 2019 20:02:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="XXAfyk4a"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=sifive.com header.i=@sifive.com header.b="XRN9VSnX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F67E2075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sifive.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:Message-ID: In-Reply-To:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=wjyXdWb3uOOcOHDMJyJamTHMWXZ6YI7t//z8r+NjdGA=; b=XXAfyk4az8E896 mSLGQtYIAs8wkhXbxqt0QywSiiolRhcEuUID4uUoR+eRKpRg2mor8GUnli++SwCMwy/YsiGEhKoCB ApBLD4H0ydmuRH6TdsJlrYewHAznQq3TUeZcq/CGLMI/SoMJMcnjiD8+SYf6rtm8vGXbPCKGE5o3L RSsnbpL+sthM2WFtBa5sKIuOJRDxmKvJHHlUKxI5gHNhQnFChvGoSSDMIMGZjXQPVRzP1NYX6Wxue WmV2mOcsTmSB5AYGBZGPza/ts8XGACsJ3rf9gx4wfnh5t0wGbLwHSCaAn+73E9id+1R6G/IRiiupy TMbaBCIYI2UXJswdXMXg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLCTr-0005Lx-IL; Mon, 29 Apr 2019 20:02:27 +0000 Received: from mail-it1-x144.google.com ([2607:f8b0:4864:20::144]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLCTn-0005L9-GH for linux-riscv@lists.infradead.org; Mon, 29 Apr 2019 20:02:25 +0000 Received: by mail-it1-x144.google.com with SMTP id z4so1029867itc.3 for ; Mon, 29 Apr 2019 13:02:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=d5+AR4ZQ6S8Je85I3GXhGfH5pQCSFdPGrCwlud052ps=; b=XRN9VSnXHB9YOZLhHV+j78/FmX9TQONi+10x6wv8ySgEM5Q3gC4vGptmW/bxkiWCCY rbcj40eh19ktqbvfBBaI7hdAi4X7nV/L6e/YdSS+D+EnzRxv2YhH95gH9aH/gutPNhO4 RJsx+Ng3drdHuugTlgCMR2KJLCwrOUInFIlaTNKgT+fEPSEflUTe81/58oCezp2WB53J Tdx9M6r9uvjF5dJT3y8Nur7B6mBnp1vd2obduvs8Sw5WW76/Khxa+GnxKWThbOxThEYI WW9SEpLLQwn3CoVL/FBE6o4G0S4hGvPjxIUy76C2Ys9mrLSEiwClLRCuBLFDnHirvptg mgMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=d5+AR4ZQ6S8Je85I3GXhGfH5pQCSFdPGrCwlud052ps=; b=Tioy9f++UHImH7DYGuiSmlapykjhhQ8lDJRPRzNwxFazgySVswjwK4A4lUX7DwNBSP N7f2hUfwI1oppT6ROnAQeNlyTcGw6BvSx79Qpd0kk8j+t9P/I6lUHN651SCmSdc5TIFe VmPGMsDqTO2IAdmIINyldX4ljPS4x6OgOGLXXDaa6HYZp5sYsLCjJ2u0RfYRZyramzpW +1KgPvgtXyGl1/8lzqNcjaVpbTjVrqlfFaSWSXibz625CX0/DDkJqcPQL+pCx0cE27BN 6L8iAXugBU2rC3wohFnA8X0eGt6BUnhBWsf9nLAKK/FhI3VPLIJf0IQDIlBokjQ1w4BK 94ng== X-Gm-Message-State: APjAAAWirmXhtVrsH1tcZ/90ILOPdV18pT9mk5oSVLpGCQgtbRSStSFR HXYGai2M81NiD5ZwL2wQQInoBQ== X-Google-Smtp-Source: APXvYqw118+txrOO593MhkfuosJ78cNcNeAwZ0b8WAls8UIMDjjD/RyZt63kf1zMwrwLeq+0e7uoZQ== X-Received: by 2002:a24:1f06:: with SMTP id d6mr645397itd.11.1556568142581; Mon, 29 Apr 2019 13:02:22 -0700 (PDT) Received: from localhost (c-73-95-159-87.hsd1.co.comcast.net. [73.95.159.87]) by smtp.gmail.com with ESMTPSA id v25sm7723994ioh.41.2019.04.29.13.02.21 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 29 Apr 2019 13:02:21 -0700 (PDT) Date: Mon, 29 Apr 2019 13:02:21 -0700 (PDT) From: Paul Walmsley X-X-Sender: paulw@viisi.sifive.com To: Anup Patel Subject: Re: [PATCH] tty: Don't force RISCV SBI console as preferred console In-Reply-To: Message-ID: References: <20190425133435.56065-1-anup.patel@wdc.com> <9a8be7ef-e62e-2a93-9170-e3dc70dfb25f@wdc.com> <20190426062133.GA28529@infradead.org> User-Agent: Alpine 2.21.9999 (DEB 301 2018-08-15) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190429_130223_553167_75A9FEEC X-CRM114-Status: GOOD ( 15.14 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Palmer Dabbelt , Greg Kroah-Hartman , Anup Patel , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Christoph Hellwig , Atish Patra , Albert Ou , Jiri Slaby , "linux-riscv@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, 26 Apr 2019, Anup Patel wrote: > On Fri, Apr 26, 2019 at 11:51 AM Christoph Hellwig wrote: > > > > On Thu, Apr 25, 2019 at 09:41:21PM -0700, Atish Patra wrote: > > > Do we even need HVC_SBI console to be enabled by default? Disabling > > > CONFIG_HVC_RISCV_SBI seems to be fine while running in QEMU. > > > > > > If we don't need it, I suggest we should remove the config option from > > > defconfig in addition to this patch. > > > > I think the whole concept of the SBI console is a little dangerous. > > It means that for one piece of physical hardware (usually the uart) > > we have two entiries (the M-mode firmware and the OS) in control, > > which tends to rarely end well. > > I think the SBI console is only useful for early SOC bringup and early > SOC debugging when most drivers are not available in upstream > kernel. It cannot (and should not) be used in production deployments. Usually the primary use-case for an abstract console interface is for desktop and server users. Usually Linux distributions want a hardware platform-specific bootloader or BIOS to specify and control the console. Originally I suspect this was implemented in the SBI for semi-hosting purposes, but that's no longer really applicable. - Paul _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv