From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754860Ab0DHFoQ (ORCPT ); Thu, 8 Apr 2010 01:44:16 -0400 Received: from mail-pz0-f193.google.com ([209.85.222.193]:55361 "EHLO mail-pz0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753655Ab0DHFoP convert rfc822-to-8bit (ORCPT ); Thu, 8 Apr 2010 01:44:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=Ntlo6JgMHB3BpEQNHuGbDjSIF5vKQM2hpSqloCo1pYQk3JDFNfkHhlYsji17q60wr9 +EovZtaVPiUck2dUTUlrKQZokW/9PS7A7D6wqqEyJsS2IZ0Nw3BvNl29ajjBaeYNh4ap qv8GhdMmaC9zK5PtUtX+bZnxr5z27Epvt5GBg= MIME-Version: 1.0 In-Reply-To: <1270604552-10051-1-git-send-email-guenter.roeck@ericsson.com> References: <1270604552-10051-1-git-send-email-guenter.roeck@ericsson.com> Date: Wed, 7 Apr 2010 22:44:14 -0700 X-Google-Sender-Auth: 1478f8797610d81b Message-ID: Subject: Re: [PATCH v2] x86: Call setup_early_printk before first call to early_printk From: Yinghai Lu To: Guenter Roeck Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, x86@kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 6, 2010 at 6:42 PM, Guenter Roeck wrote: > Current code calls setup_early_printk() too late to catch the initial calls > to early_printk(). This results in those early messages not to be printed on a > serial console. Also, if there is no VGA device in the system, it will cause > bad writes into VGA memory space. This can cause problems if the VGA memory > space is used by another device in such a system. > > Fix the problem by calling setup_early_printk() immediately after the boot > command line is available, and by preventing early_printk() to print anything > before setup_early_printk() was executed. > > Also removed conditional output "Kernel alive". > > Signed-off-by: Guenter Roeck > --- > The first version of this patch used the headline >    x86: Do not write to VGA memory space if CONFIG_VGA_CONSOLE is undefined > I changed the headline to reflect its expanded scope. > > I removed the "Kernel alive" message because I don't see how console_loglevel > can ever be equal to 10 when the code is executed. An alternative might be > (if that possibility exists after all) to move it after the call to > setup_early_printk(). > >  arch/x86/include/asm/setup.h   |    2 ++ >  arch/x86/kernel/early_printk.c |    5 ++++- >  arch/x86/kernel/head32.c       |    4 ++++ >  arch/x86/kernel/head64.c       |    7 ++++--- >  4 files changed, 14 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h > index 86b1506..83847af 100644 > --- a/arch/x86/include/asm/setup.h > +++ b/arch/x86/include/asm/setup.h > @@ -93,6 +93,8 @@ void *extend_brk(size_t size, size_t align); >                        : : "i" (sz));                                  \ >        } > > +int __init setup_early_printk(char *buf); > + >  #ifdef __i386__ > >  void __init i386_start_kernel(void); > diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c > index b9c830c..873f1cd 100644 > --- a/arch/x86/kernel/early_printk.c > +++ b/arch/x86/kernel/early_printk.c > @@ -170,6 +170,9 @@ asmlinkage void early_printk(const char *fmt, ...) >        int n; >        va_list ap; > > +       if (!early_console_initialized) > +               return; > + if someone specify "earlyprintk", early_console will still point to early_vga_console... prefer to set early_console to NULL, and here change to if (!early_console) { printk(fmt, vargs) return; } >        va_start(ap, fmt); >        n = vscnprintf(buf, sizeof(buf), fmt, ap); >        early_console->write(early_console, buf, n); > @@ -191,7 +194,7 @@ static inline void early_console_register(struct console *con, int keep_early) >        register_console(early_console); >  } > > -static int __init setup_early_printk(char *buf) > +int __init setup_early_printk(char *buf) >  { >        int keep; > > diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c > index b2e2460..e2e9c2b 100644 > --- a/arch/x86/kernel/head32.c > +++ b/arch/x86/kernel/head32.c > @@ -30,6 +30,10 @@ static void __init i386_default_early_setup(void) > >  void __init i386_start_kernel(void) >  { > +#ifdef CONFIG_EARLY_PRINTK > +       setup_early_printk(boot_command_line); > +#endif > + >  #ifdef CONFIG_X86_TRAMPOLINE >        /* >         * But first pinch a few for the stack/trampoline stuff > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index 7147143..1b4d6b2 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -88,9 +88,6 @@ void __init x86_64_start_kernel(char * real_mode_data) >        } >        load_idt((const struct desc_ptr *)&idt_descr); > > -       if (console_loglevel == 10) > -               early_printk("Kernel alive\n"); > - >        x86_64_start_reservations(real_mode_data); >  } > > @@ -98,6 +95,10 @@ void __init x86_64_start_reservations(char *real_mode_data) >  { >        copy_bootdata(__va(real_mode_data)); > > +#ifdef CONFIG_EARLY_PRINTK > +       setup_early_printk(boot_command_line); > +#endif you may need to search "earlyprintk" and cut the "earlyprintk=....." string out at first, and then use that string to call setup_early_printk() YH