From patchwork Thu Apr 30 16:14:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alper Nebi Yasak X-Patchwork-Id: 214045 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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 C5AC9C47247 for ; Thu, 30 Apr 2020 16:16:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F83320873 for ; Thu, 30 Apr 2020 16:16:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="sosUSrAu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727113AbgD3QQe (ORCPT ); Thu, 30 Apr 2020 12:16:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726405AbgD3QQd (ORCPT ); Thu, 30 Apr 2020 12:16:33 -0400 Received: from mail-lj1-x242.google.com (mail-lj1-x242.google.com [IPv6:2a00:1450:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF708C035494; Thu, 30 Apr 2020 09:16:32 -0700 (PDT) Received: by mail-lj1-x242.google.com with SMTP id f18so7082335lja.13; Thu, 30 Apr 2020 09:16:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=dcawBkXikPYOd9gFykEVGPuWXUWfQrJeZCwUFjbXlT4=; b=sosUSrAuUHwXK5OEpDrkqaJHrO0GGy0Ln5+fNdN+gN6s5xxybYMfk62DTRz82hFfDW 3WsUtL5mZtTtjasdrGDXuLX2ENo0nhL8CRdGd74HWHwz3Y/lLcmgVn8w01cgM9gIYSWy 1ClW/qZfGqJQKSpQZiLtz7DccWTt1sbgjnej1CuSydRY/DBLa+BQdaaVd4SgxYuTZAc+ 2YgxHtxvdynliAeIBWW300Rq2M7JTEnyXdt/G4CdzegQM8ORS3/eBubBGzy2nENr9s66 tMOSZY6mY7hx0HwZufKzxtYA8dCj2iV167701I6iC3ADwXddcvMiFgS2X52N8DC6+Luj 21rA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=dcawBkXikPYOd9gFykEVGPuWXUWfQrJeZCwUFjbXlT4=; b=o08cn9zMoA4uM9+4lnDDW67hx5RyLW8+Tj8kRk0OuF2UnscoSKB3bLPXUKuviS3bpZ maQYdMqt9s9Et2HVBR4ZhaPsgHVXkdeBsVwOGE5Aa6eL5D19jNQZWGW8CB1W4jVQwNFz P0fzNYBs2EXMEyPdadM1mC0A2phOC1NqCZnCPDwobtGM45HLFYzn3Obfn6vLSxpZLZWj bGaxgXs3QOS68uKdNgLgvjQnMoyPtuqZEzhgD9u22Qc8H001P7+cYW+eIhyX9QDMoKuq Ihuafqjbqw9kKj+abPdH++fOwbPf3SBHLluVhotDI05NIVCB4r33IxbF6Xyrx2INMJzj Alaw== X-Gm-Message-State: AGi0Puam89ACaSus3+r+ICNVx3h2XvxBGgecdDzotc5mwrnw2hA3O6Ls 3owdKH/bFjDC0aCc9nfYKPI= X-Google-Smtp-Source: APiQypJlHPjg7i2J2gTNDSPTCeeNvzQBhsBhfepNh86Pej0Lou55gA4cVl+9dZI3HWGt3Ys5ggHMhQ== X-Received: by 2002:a2e:b012:: with SMTP id y18mr44709ljk.238.1588263391301; Thu, 30 Apr 2020 09:16:31 -0700 (PDT) Received: from localhost.localdomain ([178.233.178.9]) by smtp.gmail.com with ESMTPSA id k6sm60638lfm.91.2020.04.30.09.16.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2020 09:16:30 -0700 (PDT) From: Alper Nebi Yasak To: Greg Kroah-Hartman , Jiri Slaby , Petr Mladek , Sergey Senozhatsky Cc: linux-serial@vger.kernel.org, Steven Rostedt , Alper Nebi Yasak , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Andrew Morton , Andy Shevchenko , Arvind Sankar , Benjamin Herrenschmidt , "David S. Miller" , Feng Tang Subject: [RFC PATCH v2 1/3] printk: Add function to set console to preferred console's driver Date: Thu, 30 Apr 2020 19:14:35 +0300 Message-Id: <20200430161438.17640-2-alpernebiyasak@gmail.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200430161438.17640-1-alpernebiyasak@gmail.com> References: <20200430161438.17640-1-alpernebiyasak@gmail.com> MIME-Version: 1.0 Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Currently, add_preferred_console sets a preferred console, but doesn't actually change /dev/console to match it. That part is handled within register_device, where a newly registered console driver will be set as /dev/console if it matches the preferred console. However, if the relevant driver is already registered, the only way to set it as /dev/console is by un-registering and re-registering it. An example is the xenfb_make_preferred_console() function: console_lock(); for_each_console(c) { if (!strcmp(c->name, "tty") && c->index == 0) break; } console_unlock(); if (c) { unregister_console(c); c->flags |= CON_CONSDEV; c->flags &= ~CON_PRINTBUFFER; /* don't print again */ register_console(c); } The code above was introduced in commit 9e124fe16ff2 ("xen: Enable console tty by default in domU if it's not a dummy"). In short, it's aim is to set VT as the preferred console only after a working framebuffer is registered and thus VT is not the dummy device. This patch introduces an update_console_to_preferred function that handles the necessary /dev/console change. With this change, the example above can be replaced with: console_lock(); add_preferred_console("tty", 0, NULL); update_console_to_preferred(); console_unlock(); More importantly, these two calls can be moved to vt.c in order to bump its priority when a non-dummy backend for it is introduced, solving that problem in general. Signed-off-by: Alper Nebi Yasak --- Changes in v2: - Use the correct format when referencing a commit include/linux/console.h | 1 + kernel/printk/printk.c | 56 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+) diff --git a/include/linux/console.h b/include/linux/console.h index 75dd20650fbe..4b3fa34be245 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -172,6 +172,7 @@ enum con_flush_mode { }; extern int add_preferred_console(char *name, int idx, char *options); +extern int update_console_to_preferred(void); extern void register_console(struct console *); extern int unregister_console(struct console *); extern struct console *console_drivers; diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 6ede4a7222e6..efda422203e4 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2240,12 +2240,68 @@ __setup("console=", console_setup); * be used by arch-specific code either to override the user or more * commonly to provide a default console (ie from PROM variables) when * the user has not supplied one. + * + * Preferences set by this function don't take effect until the next + * time a matching driver for the preferred console is registered. If a + * matching driver was already registered, @update_console_to_preferred + * function can be used to set that as the preferred console driver. */ int add_preferred_console(char *name, int idx, char *options) { return __add_preferred_console(name, idx, options, NULL, false); } +/** + * update_console_to_preferred - set console to the preferred console's driver. + * + * Updates console_drivers and CON_CONSDEV flags so that an already + * registered and enabled console driver matching the preferred console + * is used as /dev/console. + * + * Must be called within console_lock();. + */ +int update_console_to_preferred(void) +{ + struct console_cmdline *c = NULL; + struct console *con = NULL; + struct console *tmp = NULL; + + if (preferred_console >= 0) + c = &console_cmdline[preferred_console]; + + if (!c || !c->name[0]) + return 0; + + for_each_console(con) { + if (!con->next || !(con->next->flags & CON_ENABLED)) + continue; + if (strcmp(c->name, con->next->name) != 0) + continue; + if (con->next->index >= 0 && + con->next->index != c->index) + continue; + break; + } + + if (!con) + return -ENODEV; + + pr_info("switching to console [%s%d]\n", + con->next->name, con->next->index); + + tmp = con->next; + con->next = con->next->next; + tmp->next = console_drivers; + console_drivers = tmp; + + if (console_drivers->next) + console_drivers->next->flags &= ~CON_CONSDEV; + console_drivers->flags |= CON_CONSDEV; + has_preferred_console = true; + + return 0; +} + bool console_suspend_enabled = true; EXPORT_SYMBOL(console_suspend_enabled); From patchwork Thu Apr 30 16:14:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alper Nebi Yasak X-Patchwork-Id: 214044 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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 5661EC47247 for ; 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Thu, 30 Apr 2020 09:16:42 -0700 (PDT) Received: from localhost.localdomain ([178.233.178.9]) by smtp.gmail.com with ESMTPSA id k6sm60638lfm.91.2020.04.30.09.16.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2020 09:16:41 -0700 (PDT) From: Alper Nebi Yasak To: Greg Kroah-Hartman , Jiri Slaby , Petr Mladek , Sergey Senozhatsky Cc: linux-serial@vger.kernel.org, Steven Rostedt , Alper Nebi Yasak , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v2 3/3] printk: Preset tty0 as a pseudo-preferred console Date: Thu, 30 Apr 2020 19:14:37 +0300 Message-Id: <20200430161438.17640-4-alpernebiyasak@gmail.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200430161438.17640-1-alpernebiyasak@gmail.com> References: <20200430161438.17640-1-alpernebiyasak@gmail.com> MIME-Version: 1.0 Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org The ACPI SPCR (Serial Port Console Redirection) table from a machine's firmware can specify a serial console which can be used for earlycon. However, in at least ARM64 systems the same device is also set up as the preferred console. Presumably due to the order of acpi_parse_spcr and VT's register_device calls, setting the specified console as the preferred one can prevent registering VT as a console. This might look appropriate for machines which do not have or need working graphics and whose users most likely have access to a serial port. However, the use of SPCR tables may not be limited these. For example, ARM64 QEMU virtual machines include a SPCR table regardless of the existence of a graphics output or even the nonexistence of a serial console. Or server hardware which has a SPCR table can be repurposed into a workstation with the addition of a graphics card. As a result, boot messages and early userspace prompts can go to an unexpected console. This patch presets tty0 as a pseudo-preferred console at compile-time to ensure that CONFIG_VT_CONSOLE always results in the VT console getting registered. With this, VT can get registered, these other consoles are preferred when VT is a dummy, but we can also bump up VTs preference when working graphics are available. Without this patch, an ARM64 QEMU virtual machine has roughly the following order of console events and consoles: # Without earlycon: $ sudo dmesg | grep -i "console\|printk\|tty[0-9a-z]" | grep -v systemd [ 0.000000] ACPI: SPCR: console: pl011,mmio,0x9000000,9600 [ 0.000250] Console: colour dummy device 80x25 [ 0.140955] ARMH0011:00: ttyAMA0 at MMIO 0x9000000 (irq = 4, base_baud = 0) is a SBSA [ 0.317189] printk: console [ttyAMA0] enabled [ 3.540272] Console: switching to colour frame buffer device 150x42 $ cat /proc/consoles ttyAMA0 -W- (EC p a) 204:64 # With earlycon: $ sudo dmesg | grep -i "console\|printk\|tty[0-9a-z]" | grep -v systemd [ 0.000000] ACPI: SPCR: console: pl011,mmio,0x9000000,9600 [ 0.000000] printk: bootconsole [pl11] enabled [ 0.002064] Console: colour dummy device 80x25 [ 0.324415] ARMH0011:00: ttyAMA0 at MMIO 0x9000000 (irq = 4, base_baud = 0) is a SBSA [ 0.327047] printk: console [ttyAMA0] enabled [ 0.329139] printk: bootconsole [pl11] disabled [ 3.704937] Console: switching to colour frame buffer device 150x42 $ cat /proc/consoles ttyAMA0 -W- (EC a) 204:64 In addition, boot messages aren't printed to the framebuffer (as tty0 is not registered). With this patch, boot messages are visible on the framebuffer and the information above becomes: # Without earlycon: $ sudo dmesg | grep -i "console\|printk\|tty[0-9a-z]" | grep -v systemd [ 0.000000] ACPI: SPCR: console: pl011,mmio,0x9000000,9600 [ 0.000058] Console: colour dummy device 80x25 [ 0.000266] printk: console [tty0] enabled [ 0.144615] ARMH0011:00: ttyAMA0 at MMIO 0x9000000 (irq = 4, base_baud = 0) is a SBSA [ 0.299031] printk: console [ttyAMA0] enabled [ 3.320333] Console: switching to colour frame buffer device 150x42 [ 3.329386] printk: switching to console [tty0] $ cat /proc/consoles tty0 -WU (EC p ) 4:7 ttyAMA0 -W- (E p a) 204:64 # With earlycon: $ sudo dmesg | grep -i "console\|printk\|tty[0-9a-z]" | grep -v systemd [ 0.000000] ACPI: SPCR: console: pl011,mmio,0x9000000,9600 [ 0.000000] printk: bootconsole [pl11] enabled [ 0.002326] Console: colour dummy device 80x25 [ 0.003545] printk: console [tty0] enabled [ 0.236824] ARMH0011:00: ttyAMA0 at MMIO 0x9000000 (irq = 4, base_baud = 0) is a SBSA [ 0.239243] printk: console [ttyAMA0] enabled [ 0.241324] printk: bootconsole [pl11] disabled [ 3.715086] Console: switching to colour frame buffer device 150x42 [ 3.742923] printk: switching to console [tty0] $ cat /proc/consoles tty0 -WU (EC p ) 4:7 ttyAMA0 -W- (E a) 204:64 Signed-off-by: Alper Nebi Yasak --- Changes in v2: - Fix #elif to #else (Reported-by: kbuild test robot ) - Refresh dmesg outputs with/without earlycon for next-20200430 kernel/printk/printk.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index efda422203e4..aa9f9f16860f 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -277,7 +277,19 @@ static struct console *exclusive_console; #define MAX_CMDLINECONSOLES 8 +/* + * The preferred_console and has_preferred_console variables are + * intentionally not modified to reflect this so that the first + * registered console is still used as the preferred console. + */ +#ifdef CONFIG_VT_CONSOLE +static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES] = { + [0].name = "tty", + [0].index = 0, +}; +#else static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; +#endif static int preferred_console = -1; static bool has_preferred_console;