Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933439AbbFIRBG (ORCPT ); Tue, 9 Jun 2015 13:01:06 -0400 Received: from mga09.intel.com ([134.134.136.24]:25787 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933067AbbFIRAz (ORCPT ); Tue, 9 Jun 2015 13:00:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,582,1427785200"; d="scan'208";a="740231836" Message-ID: <1433869251.26331.114.camel@linux.intel.com> Subject: Re: [PATCH v11 4/5] x86/earlyprintk: setup earlyprintk as early as possible From: Andy Shevchenko To: Alexander Kuleshov Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , LKML , Greg Kroah-Hartman , Borislav Petkov , Mark Rustad , Yinghai Lu Date: Tue, 09 Jun 2015 20:00:51 +0300 In-Reply-To: <1433848301-5296-1-git-send-email-kuleshovmail@gmail.com> References: <1433848247-3550-1-git-send-email-kuleshovmail@gmail.com> <1433848301-5296-1-git-send-email-kuleshovmail@gmail.com> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9-1+b1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5700 Lines: 169 On Tue, 2015-06-09 at 17:11 +0600, Alexander Kuleshov wrote: > 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 and real hardware, so early_printk() is usable and > prints to serial console right after setup_early_printk function called. > One topic to discuss below. > Signed-off-by: Alexander Kuleshov > --- > arch/x86/include/asm/setup.h | 6 ++++++ > arch/x86/kernel/early_printk.c | 33 ++++++++++++++++++++++++++++++--- > arch/x86/kernel/head32.c | 3 +++ > arch/x86/kernel/head64.c | 5 ++++- > 4 files changed, 43 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h > index 59efd0d..180bda4 100644 > --- a/arch/x86/include/asm/setup.h > +++ b/arch/x86/include/asm/setup.h > @@ -120,0 +120,0 @@ 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 */ > +extern int __init setup_early_serial_console(void); > +#else > +static inline int __init setup_early_serial_console(void) { return 0; } > +#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..6442cd2 100644 > --- a/arch/x86/kernel/early_printk.c > +++ b/arch/x86/kernel/early_printk.c > @@ -342,19 +342,22 @@ static int __init setup_early_printk(char *buf) > keep = (strstr(buf, "keep") != NULL); > > while (*buf != '\0') { > - if (!strncmp(buf, "serial", 6)) { > + if (!strncmp(buf, "serial", 6) && > + early_serial_console.index == -1) { > buf += 6; > early_serial_init(buf); > early_console_register(&early_serial_console, keep); > if (!strncmp(buf, ",ttyS", 5)) > buf += 5; > } > - if (!strncmp(buf, "ttyS", 4)) { > + if (!strncmp(buf, "ttyS", 4) && > + early_serial_console.index == -1) { > early_serial_init(buf + 4); > early_console_register(&early_serial_console, keep); > } > #ifdef CONFIG_PCI > - if (!strncmp(buf, "pciserial", 9)) { > + if (!strncmp(buf, "pciserial", 9) && > + early_serial_console.index == -1) { > early_pci_serial_init(buf + 9); > early_console_register(&early_serial_console, keep); > buf += 9; /* Keep from match the above "serial" */ > @@ -385,4 +388,28 @@ 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); > +} I'm still not convincing by this code to be in that form and here. What about to refactor setup_early_printk() to helper which will do parse parameters to a let say structure where one of the flag will be struct early_printk_param { … const char *arg; bool serial; } Your function will be something like this struct early_printk_param epp; parse_early_printk_param(&epp); if (!epp->serial) return /* whatever error code */; return setup_early_printk(epp.arg); > + > early_param("earlyprintk", setup_early_printk); > diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c > index f28d10f..908ee47 100644 > --- a/arch/x86/kernel/head32.c > +++ b/arch/x86/kernel/head32.c > @@ -38,0 +38,0 @@ asmlinkage __visible void __init i386_start_kernel(void) > /* Allocate early log buffer */ > setup_log_buf(1); > > + setup_early_serial_console(); > + 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 53662d2..041be2c 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -176,0 +176,0 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) > > /* Allocate early log buffer */ > setup_log_buf(1); > > + setup_early_serial_console(); > + early_printk("Early printk is initialized\n"); > + > /* > * Load microcode early on BSP. > */ -- Andy Shevchenko Intel Finland Oy -- 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/