From nobody Fri Dec 19 12:31:07 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0AA3417741; Wed, 3 Jul 2024 10:06:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720001200; cv=none; b=W2/lE4XaxRpSErBomR4GPdqHbFvXo7ZxOmNtuyPuJtEoBP2VrOCkcCbqOOdhmMRqQgc10andxi/zUECoHZmAOrA51KsCH4Rh9XrbU4QqPa+hKK/DykcMkzE+g0Je4c6sqq4o6LdBIpY/w+a7F5hu2QKKWFIrqtIGFjgQGd+2E2A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720001200; c=relaxed/simple; bh=+9uLGhO2nA/u4DYx/nC1szVU+6fu/INfo+jo2Nez2Wg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OWIvgz4BQSC+7wAs4oJ/ybrJIL7zUXMsynyqYRbysh3wrxfHjcHpOy8SnQhMQ55Is1sBjrYM3zwDz5/5q6WaWf87PGNcXKgI2uFyUeLUaEkgiTGT3fvbLEspaYjWDjR5ny0P4+JuBo0b5/NJmUCACSQDN4bZWdUqADF/VCnBy9s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=QLvqQT6N; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="QLvqQT6N" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1720001199; x=1751537199; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=+9uLGhO2nA/u4DYx/nC1szVU+6fu/INfo+jo2Nez2Wg=; b=QLvqQT6NJm6kQfJVTX9Pggu2P73mWAvbz2TvDbbnDvLZrisACMQ3OrmP 0/p63AamHihQl6joshFyGvx3/TwH/hK7sx4r6rfJV/qaKdO2M3Bt4/kpm HO969C2008eadN/MWlHh+4gASr/p6xDCiaPhXoJszz5ftnzrEnzhTEDIc 6zeoF0umnQnaS7wr3++vhYIrCrXzIzkgRj5/v5251t1qewuSQ+5jT5G8x ED+qtTxR+vEBK35D/2tPH+hMmRRqnUxzS/2rdM79DNIsjQLHdRRhXXRBj vdUon4C3v/WDq/MRbrE3Q+ZK817G48ueNDn2PXjF82SkZiG7i6aB+sm1K A==; X-CSE-ConnectionGUID: BedvBbiJTyOHKkr4/P73Ow== X-CSE-MsgGUID: N4uk7JVySLicFMP5407w4w== X-IronPort-AV: E=McAfee;i="6700,10204,11121"; a="21093779" X-IronPort-AV: E=Sophos;i="6.09,181,1716274800"; d="scan'208";a="21093779" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jul 2024 03:06:38 -0700 X-CSE-ConnectionGUID: k1kr0H5VTTK2Ycu2RYGmhQ== X-CSE-MsgGUID: NulDsKBVRbKjwRapFu8qSQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,181,1716274800"; d="scan'208";a="69384979" Received: from pgcooper-mobl3.ger.corp.intel.com (HELO tlindgre-MOBL1.intel.com) ([10.245.244.185]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jul 2024 03:06:33 -0700 From: Tony Lindgren To: Jonathan Corbet , Greg Kroah-Hartman , Jiri Slaby , Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky Cc: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , linux-serial@vger.kernel.org, Tony Lindgren , Dhruva Gole , Sebastian Reichel , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/3] printk: Add match_devname_and_update_preferred_console() Date: Wed, 3 Jul 2024 13:06:08 +0300 Message-ID: <20240703100615.118762-2-tony.lindgren@linux.intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703100615.118762-1-tony.lindgren@linux.intel.com> References: <20240703100615.118762-1-tony.lindgren@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Let's add match_devname_and_update_preferred_console() for driver subsystems to call during init when the console is ready, and it's character device name is known. For now, we use it only for the serial layer to allow console=3DDEVNAME:0.0 style hardware based addressing for consoles. The earlier attempt on doing this caused a regression with the kernel command line console order as it added calling __add_preferred_console() again later on during init. A better approach was suggested by Petr where we add the deferred console to the console_cmdline[] and update it later on when the console is ready. Suggested-by: Petr Mladek Co-developed-by: Petr Mladek Signed-off-by: Tony Lindgren Reviewed-by: Petr Mladek --- include/linux/printk.h | 4 ++ kernel/printk/console_cmdline.h | 1 + kernel/printk/printk.c | 103 +++++++++++++++++++++++++++----- 3 files changed, 93 insertions(+), 15 deletions(-) diff --git a/include/linux/printk.h b/include/linux/printk.h index 65c5184470f1..7239976698e4 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -60,6 +60,10 @@ static inline const char *printk_skip_headers(const char= *buffer) #define CONSOLE_LOGLEVEL_DEFAULT CONFIG_CONSOLE_LOGLEVEL_DEFAULT #define CONSOLE_LOGLEVEL_QUIET CONFIG_CONSOLE_LOGLEVEL_QUIET =20 +int match_devname_and_update_preferred_console(const char *match, + const char *name, + const short idx); + extern int console_printk[]; =20 #define console_loglevel (console_printk[0]) diff --git a/kernel/printk/console_cmdline.h b/kernel/printk/console_cmdlin= e.h index 3ca74ad391d6..0ab573b6d4dc 100644 --- a/kernel/printk/console_cmdline.h +++ b/kernel/printk/console_cmdline.h @@ -6,6 +6,7 @@ struct console_cmdline { char name[16]; /* Name of the driver */ int index; /* Minor dev. to use */ + char devname[32]; /* DEVNAME:0.0 style device name */ bool user_specified; /* Specified by command line vs. platform */ char *options; /* Options for the driver */ #ifdef CONFIG_A11Y_BRAILLE_CONSOLE diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index dddb15f48d59..7d91593f0ecf 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2429,18 +2429,23 @@ static void set_user_specified(struct console_cmdli= ne *c, bool user_specified) console_set_on_cmdline =3D 1; } =20 -static int __add_preferred_console(const char *name, const short idx, char= *options, +static int __add_preferred_console(const char *name, const short idx, + const char *devname, char *options, char *brl_options, bool user_specified) { struct console_cmdline *c; int i; =20 + if (!name && !devname) + return -EINVAL; + /* * We use a signed short index for struct console for device drivers to * indicate a not yet assigned index or port. However, a negative index - * value is not valid for preferred console. + * value is not valid when the console name and index are defined on + * the command line. */ - if (idx < 0) + if (name && idx < 0) return -EINVAL; =20 /* @@ -2448,9 +2453,10 @@ static int __add_preferred_console(const char *name,= const short idx, char *opti * if we have a slot free. */ for (i =3D 0, c =3D console_cmdline; - i < MAX_CMDLINECONSOLES && c->name[0]; + i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]); i++, c++) { - if (strcmp(c->name, name) =3D=3D 0 && c->index =3D=3D idx) { + if ((name && strcmp(c->name, name) =3D=3D 0 && c->index =3D=3D idx) || + (devname && strcmp(c->devname, devname) =3D=3D 0)) { if (!brl_options) preferred_console =3D i; set_user_specified(c, user_specified); @@ -2461,7 +2467,10 @@ static int __add_preferred_console(const char *name,= const short idx, char *opti return -E2BIG; if (!brl_options) preferred_console =3D i; - strscpy(c->name, name, sizeof(c->name)); + if (name) + strscpy(c->name, name); + if (devname) + strscpy(c->devname, devname); c->options =3D options; set_user_specified(c, user_specified); braille_set_options(c, brl_options); @@ -2486,8 +2495,13 @@ __setup("console_msg_format=3D", console_msg_format_= setup); */ static int __init console_setup(char *str) { - char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for "ttyS" */ - char *s, *options, *brl_options =3D NULL; + static_assert(sizeof(console_cmdline[0].devname) >=3D sizeof(console_cmdl= ine[0].name) + 4); + char buf[sizeof(console_cmdline[0].devname)]; + char *brl_options =3D NULL; + char *ttyname =3D NULL; + char *devname =3D NULL; + char *options; + char *s; int idx; =20 /* @@ -2496,17 +2510,23 @@ static int __init console_setup(char *str) * for exactly this purpose. */ if (str[0] =3D=3D 0 || strcmp(str, "null") =3D=3D 0) { - __add_preferred_console("ttynull", 0, NULL, NULL, true); + __add_preferred_console("ttynull", 0, NULL, NULL, NULL, true); return 1; } =20 if (_braille_console_setup(&str, &brl_options)) return 1; =20 + /* For a DEVNAME:0.0 style console the character device is unknown early = */ + if (strchr(str, ':')) + devname =3D buf; + else + ttyname =3D buf; + /* * Decode str into name, index, options. */ - if (isdigit(str[0])) + if (ttyname && isdigit(str[0])) scnprintf(buf, sizeof(buf), "ttyS%s", str); else strscpy(buf, str); @@ -2523,12 +2543,18 @@ static int __init console_setup(char *str) #endif =20 for (s =3D buf; *s; s++) - if (isdigit(*s) || *s =3D=3D ',') + if ((ttyname && isdigit(*s)) || *s =3D=3D ',') break; - idx =3D simple_strtoul(s, NULL, 10); + + /* @idx will get defined when devname matches. */ + if (devname) + idx =3D -1; + else + idx =3D simple_strtoul(s, NULL, 10); + *s =3D 0; =20 - __add_preferred_console(buf, idx, options, brl_options, true); + __add_preferred_console(ttyname, idx, devname, options, brl_options, true= ); return 1; } __setup("console=3D", console_setup); @@ -2548,7 +2574,51 @@ __setup("console=3D", console_setup); */ int add_preferred_console(const char *name, const short idx, char *options) { - return __add_preferred_console(name, idx, options, NULL, false); + return __add_preferred_console(name, idx, NULL, options, NULL, false); +} + +/** + * match_devname_and_update_preferred_console - Update a preferred console + * when matching devname is found. + * @devname: DEVNAME:0.0 style device name + * @name: Name of the corresponding console driver, e.g. "ttyS" + * @idx: Console index, e.g. port number. + * + * The function checks whether a device with the given @devname is + * preferred via the console=3DDEVNAME:0.0 command line option. + * It fills the missing console driver name and console index + * so that a later register_console() call could find (match) + * and enable this device. + * + * It might be used when a driver subsystem initializes particular + * devices with already known DEVNAME:0.0 style names. And it + * could predict which console driver name and index this device + * would later get associated with. + * + * Return: 0 on success, negative error code on failure. + */ +int match_devname_and_update_preferred_console(const char *devname, + const char *name, + const short idx) +{ + struct console_cmdline *c =3D console_cmdline; + int i; + + if (!devname || !strlen(devname) || !name || !strlen(name) || idx < 0) + return -EINVAL; + + for (i =3D 0; i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]); + i++, c++) { + if (!strcmp(devname, c->devname)) { + pr_info("associate the preferred console \"%s\" with \"%s%d\"\n", + devname, name, idx); + strscpy(c->name, name); + c->index =3D idx; + return 0; + } + } + + return -ENOENT; } =20 bool console_suspend_enabled =3D true; @@ -3318,8 +3388,11 @@ static int try_enable_preferred_console(struct conso= le *newcon, int i, err; =20 for (i =3D 0, c =3D console_cmdline; - i < MAX_CMDLINECONSOLES && c->name[0]; + i < MAX_CMDLINECONSOLES && (c->name[0] || c->devname[0]); i++, c++) { + /* Console not yet initialized? */ + if (!c->name[0]) + continue; if (c->user_specified !=3D user_specified) continue; if (!newcon->match || --=20 2.45.2 From nobody Fri Dec 19 12:31:07 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1F1F313D2BE; Wed, 3 Jul 2024 10:06:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720001208; cv=none; b=cZY3Mk8i4mhZaOlUOpYKQm70Z0QkiTCWtLSqQQZYC7Hqm0NK5XzNvo094SBlvvWeROAg/6V/nY1GLmtl2awy+9DYpC35iojFUt3FyS1crwyh0vawsazpYGLV6oaz5QzH6HT6PYHou+y0SWL5BUVp8LMLWJaJJaHGG/9pb02lcfg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720001208; c=relaxed/simple; bh=eaqYx0tP7xE/NKkuA/s0zoqf+t488PDvb5zZwZQtox0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=B7nd7w8SSrNUn4uu1xFBFWkVZZDcI7kiphXb0qxftQ2JdCGw7tP7eE+8mCT5juJAv+x7/bb+cU4GAec63Ovq20vFubd4cb0PpOjL7I+arwO86wsuTnvZ5DwG/2eTsF4yJdbfAQ0eCJwt13EjoErViwMnhUNe/YtmxYsrLiYNVEM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=QIrHcnmR; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="QIrHcnmR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1720001207; x=1751537207; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=eaqYx0tP7xE/NKkuA/s0zoqf+t488PDvb5zZwZQtox0=; b=QIrHcnmRee2whOWm5p8CS6bS3CUgFCi93N/GqbL902y080axvX7R5yQD XVd+IWfnGsw0jFHuNk1tY5vC2/bgfmbOa3xIoCOLIWrzSvv22XXZ64s/o srL8XYS7HLmeC2L9vBlEsTgREBS8yeM2fKDoyeZI+CPPCivtT8EmFlJS6 xAuY4SWrhQxEQHBAXQ4hCPtobwnp+7/j1CD4g8YOklP2MDiSKskM4BsHn FRpJ7M5yNXSfltmqw6tGvhimb4ihYpp1EBFo/Yv/tOtcE5Z/jMFkU05hs EnQ9UWkReFmlpTrLFoa3Hvo51ttgwuDq7v/0tQr6pIM7eK7f42sif7YZU w==; X-CSE-ConnectionGUID: nDgnDkldSKihA8h68YzmNg== X-CSE-MsgGUID: YPlLRyMcSt2P4/MfIgRaCw== X-IronPort-AV: E=McAfee;i="6700,10204,11121"; a="21093801" X-IronPort-AV: E=Sophos;i="6.09,181,1716274800"; d="scan'208";a="21093801" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jul 2024 03:06:46 -0700 X-CSE-ConnectionGUID: HEWMSNoRQg+kEy2LcU9Eiw== X-CSE-MsgGUID: r8ET8w7VTySEIY8hsocqrQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,181,1716274800"; d="scan'208";a="69385006" Received: from pgcooper-mobl3.ger.corp.intel.com (HELO tlindgre-MOBL1.intel.com) ([10.245.244.185]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jul 2024 03:06:41 -0700 From: Tony Lindgren To: Jonathan Corbet , Greg Kroah-Hartman , Jiri Slaby , Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky Cc: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , linux-serial@vger.kernel.org, Tony Lindgren , Dhruva Gole , Sebastian Reichel , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] serial: core: Add serial_base_match_and_update_preferred_console() Date: Wed, 3 Jul 2024 13:06:09 +0300 Message-ID: <20240703100615.118762-3-tony.lindgren@linux.intel.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703100615.118762-1-tony.lindgren@linux.intel.com> References: <20240703100615.118762-1-tony.lindgren@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Let's add serial_base_match_and_update_preferred_console() for consoles using DEVNAME:0.0 style naming. The earlier approach to add it caused issues in the kernel command line ordering as we were calling __add_preferred_console() again for the deferred consoles. Signed-off-by: Tony Lindgren --- drivers/tty/serial/serial_base.h | 16 ++++++++++++ drivers/tty/serial/serial_base_bus.c | 37 ++++++++++++++++++++++++++++ drivers/tty/serial/serial_core.c | 4 +++ 3 files changed, 57 insertions(+) diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_b= ase.h index b6c38d2edfd4..0d50db5b660b 100644 --- a/drivers/tty/serial/serial_base.h +++ b/drivers/tty/serial/serial_base.h @@ -49,3 +49,19 @@ void serial_ctrl_unregister_port(struct uart_driver *drv= , struct uart_port *port =20 int serial_core_register_port(struct uart_driver *drv, struct uart_port *p= ort); void serial_core_unregister_port(struct uart_driver *drv, struct uart_port= *port); + +#ifdef CONFIG_SERIAL_CORE_CONSOLE + +int serial_base_match_and_update_preferred_console(struct uart_driver *drv, + struct uart_port *port); + +#else + +static inline +int serial_base_match_and_update_preferred_console(struct uart_driver *drv, + struct uart_port *port) +{ + return 0; +} + +#endif diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/seri= al_base_bus.c index 4df2a4b10445..d822499ba9d6 100644 --- a/drivers/tty/serial/serial_base_bus.c +++ b/drivers/tty/serial/serial_base_bus.c @@ -8,6 +8,7 @@ * The serial core bus manages the serial core controller instances. */ =20 +#include #include #include #include @@ -204,6 +205,42 @@ void serial_base_port_device_remove(struct serial_port= _device *port_dev) put_device(&port_dev->dev); } =20 +#ifdef CONFIG_SERIAL_CORE_CONSOLE + +/** + * serial_base_match_and_update_preferred_console - Match and update a pre= ferred console + * @drv: Serial port device driver + * @port: Serial port instance + * + * Tries to match and update the preferred console for a serial port for + * the kernel command line option console=3DDEVNAME:0.0. + * + * Cannot be called early for ISA ports, depends on struct device. + * + * Return: 0 on success, negative error code on failure. + */ +int serial_base_match_and_update_preferred_console(struct uart_driver *drv, + struct uart_port *port) +{ + const char *port_match __free(kfree) =3D NULL; + int ret; + + port_match =3D kasprintf(GFP_KERNEL, "%s:%d.%d", dev_name(port->dev), + port->ctrl_id, port->port_id); + if (!port_match) + return -ENOMEM; + + ret =3D match_devname_and_update_preferred_console(port_match, + drv->dev_name, + port->line); + if (ret =3D=3D -ENOENT) + return 0; + + return ret; +} + +#endif + static int serial_base_init(void) { int ret; diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_c= ore.c index 2a8006e3d687..9a18d0b95a41 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -3422,6 +3422,10 @@ int serial_core_register_port(struct uart_driver *dr= v, struct uart_port *port) if (ret) goto err_unregister_ctrl_dev; =20 + ret =3D serial_base_match_and_update_preferred_console(drv, port); + if (ret) + goto err_unregister_port_dev; + ret =3D serial_core_add_one_port(drv, port); if (ret) goto err_unregister_port_dev; --=20 2.45.2 From nobody Fri Dec 19 12:31:07 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 726A913D2BE; Wed, 3 Jul 2024 10:06:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; 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charset="utf-8" From: Tony Lindgren Document the console option for DEVNAME:0.0 style addressing for serial ports. Suggested-by: Sebastian Reichel Signed-off-by: Tony Lindgren Reviewed-by: Dhruva Gole Reviewed-by: Petr Mladek --- .../admin-guide/kernel-parameters.txt | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 27ec49af1bf2..11e57ba2985c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -788,6 +788,25 @@ Documentation/networking/netconsole.rst for an alternative. =20 + :.[,options] + Use the specified serial port on the serial core bus. + The addressing uses DEVNAME of the physical serial port + device, followed by the serial core controller instance, + and the serial port instance. The options are the same + as documented for the ttyS addressing above. + + The mapping of the serial ports to the tty instances + can be viewed with: + + $ ls -d /sys/bus/serial-base/devices/*:*.*/tty/* + /sys/bus/serial-base/devices/00:04:0.0/tty/ttyS0 + + In the above example, the console can be addressed with + console=3D00:04:0.0. Note that a console addressed this + way will only get added when the related device driver + is ready. The use of an earlycon parameter in addition to + the console may be desired for console output early on. + uart[8250],io,[,options] uart[8250],mmio,[,options] uart[8250],mmio16,[,options] --=20 2.45.2