Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753656AbbERJYW (ORCPT ); Mon, 18 May 2015 05:24:22 -0400 Received: from mail-la0-f48.google.com ([209.85.215.48]:35445 "EHLO mail-la0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753423AbbERJXZ (ORCPT ); Mon, 18 May 2015 05:23:25 -0400 From: Alexander Kuleshov To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: Alexander Kuleshov , Andy Shevchenko , LKML , Greg Kroah-Hartman , Borislav Petkov , Mark Rustad , Yinghai Lu Subject: [PATCH v7 3/3] x86/earlyprintk: setup earlyprintk as early as possible Date: Mon, 18 May 2015 15:23:18 +0600 Message-Id: <1431940998-21823-1-git-send-email-kuleshovmail@gmail.com> X-Mailer: git-send-email 2.4.0 In-Reply-To: <1431940756-12848-1-git-send-email-kuleshovmail@gmail.com> References: <1431940756-12848-1-git-send-email-kuleshovmail@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3953 Lines: 118 The early_printk function is usable only after the setup_early_printk will be executed. We pass 'earlyprintk' through the kernel command line, so it will be usable only after the 'parse_early_param' will be executed. This means that we have usable earlyprintk only during early boot, kernel decompression and after call of the 'parse_early_param'. This patchset makes earlyprintk usable before the call of the 'parse_early_param'. This patch makes the setup_early_printk visible for head{32,64}.c. So the 'early_printk' function will be usabable after decompression of the kernel and before parse_early_param will be called. It also must be safe if CONFIG_CMDLINE_BOOL and CONFIG_CMDLINE_OVERRIDE are set, because setup_cmdline function will be called before setup_early_printk. It provides earlyprintk only for serial console, because other needs in ioremap which is not initialized yet. Tested it with qemu, so early_printk() is usable and prints to serial console right after setup_early_printk function called. Signed-off-by: Alexander Kuleshov --- arch/x86/include/asm/setup.h | 7 +++++++ arch/x86/kernel/early_printk.c | 24 ++++++++++++++++++++++++ arch/x86/kernel/head32.c | 6 ++++++ arch/x86/kernel/head64.c | 5 +++++ 4 files changed, 42 insertions(+) diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h index 59efd0d..4234ada 100644 --- a/arch/x86/include/asm/setup.h +++ b/arch/x86/include/asm/setup.h @@ -120,6 +120,13 @@ asmlinkage void __init x86_64_start_reservations(char *real_mode_data); #endif /* __i386__ */ void __init setup_builtin_cmdline(void); +#ifdef CONFIG_EARLY_PRINTK +/* used by arch/x86/kernel/head{32,64}.c */ +int __init setup_early_serial_console(void); +#else +int __init setup_early_serial_console(void) { } +#endif /* CONFIG_EARLY_PRINTK */ #endif /* _SETUP */ #else #define RESERVE_BRK(name,sz) \ diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c index 89427d8..0b2a626 100644 --- a/arch/x86/kernel/early_printk.c +++ b/arch/x86/kernel/early_printk.c @@ -385,4 +385,28 @@ static int __init setup_early_printk(char *buf) return 0; } +int __init setup_early_serial_console(void) +{ + char *arg; + + /* + * make sure that we have: + * "serial,0x3f8,115200" + * "serial,ttyS0,115200" + * "ttyS0,115200" + */ + arg = strstr(boot_command_line, "earlyprintk=serial"); + if (!arg) + arg = strstr(boot_command_line, "earlyprintk=ttyS"); + if (!arg) + return -1; + + arg = strstr(boot_command_line, "earlyprintk="); + + /* += strlen("earlyprintk"); */ + arg += 12; + + return setup_early_printk(arg); +} + early_param("earlyprintk", setup_early_printk); diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c index 92e8b5f..759d115 100644 --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -32,6 +32,12 @@ static void __init i386_default_early_setup(void) asmlinkage __visible void __init i386_start_kernel(void) { setup_builtin_cmdline(); + + setup_early_serial_console(); + + if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG) + early_printk("Early printk is initialized\n"); + cr4_init_shadow(); sanitize_boot_params(&boot_params); diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 346a042..6b7529a 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -174,7 +174,11 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) setup_builtin_cmdline(); + setup_early_serial_console(); + + if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG) + early_printk("Early printk is initialized\n"); + /* * Load microcode early on BSP. */ -- 2.4.0 -- 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/