From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753625Ab0DZPnt (ORCPT ); Mon, 26 Apr 2010 11:43:49 -0400 Received: from mail-bw0-f219.google.com ([209.85.218.219]:48578 "EHLO mail-bw0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751590Ab0DZPns convert rfc822-to-8bit (ORCPT ); Mon, 26 Apr 2010 11:43:48 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=TC8TMQhsAL+0y2AjheNMrF3hviz4N14aoVoMdXbsnu943eNzSDaxy4WMhizqDqdumV CS1YSt5EBTrfSvC+Os8tsXScCFE9OIoHFMoOjMTQOWOnY6nhI4a64A1UbOu29SJsGYCC Zo48tskr6n+eUqTxFQxDWibYphTQgPM//bQuY= MIME-Version: 1.0 In-Reply-To: <1271780217-27472-1-git-send-email-guenter.roeck@ericsson.com> References: <1271780217-27472-1-git-send-email-guenter.roeck@ericsson.com> Date: Mon, 26 Apr 2010 17:43:44 +0200 Message-ID: Subject: Re: [PATCH v3] x86: Do not write into VGA memory space if there is no VGA device in the system From: Bastien ROUCARIES To: Guenter Roeck Cc: linux-kernel@vger.kernel.org, penberg@cs.helsinki.fi, 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 20, 2010 at 6:16 PM, Guenter Roeck wrote: > Ensure that early_printk() does not write into VGA memory space > if there is not VGA device in the system. > > Signed-off-by: Guenter Roeck > --- > v3: > Changes are now limited to early_printk.c. Functionality is retained, meaning > there will still be output on the VGA console before setup_early_printk() > is called, but only if a VGA device is known to exist in the system. > >  arch/x86/kernel/early_printk.c |   17 +++++++++++++---- >  1 files changed, 13 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c > index b9c830c..783cb25 100644 > --- a/arch/x86/kernel/early_printk.c > +++ b/arch/x86/kernel/early_printk.c > @@ -170,10 +170,13 @@ asmlinkage void early_printk(const char *fmt, ...) >        int n; >        va_list ap; > > -       va_start(ap, fmt); > -       n = vscnprintf(buf, sizeof(buf), fmt, ap); > -       early_console->write(early_console, buf, n); > -       va_end(ap); > +       if (early_console && (early_console_initialized || > +                             boot_params.screen_info.orig_video_isVGA == 1)) { > +               va_start(ap, fmt); > +               n = vscnprintf(buf, sizeof(buf), fmt, ap); > +               early_console->write(early_console, buf, n); > +               va_end(ap); > +       } >  } Instead to this ugly if why not creating a null early_console (write will do nothing) ? >  static inline void early_console_register(struct console *con, int keep_early) > @@ -233,6 +236,12 @@ static int __init setup_early_printk(char *buf) >  #endif >                buf++; >        } > + > +       /* If there is no VGA device, don't try to use it as early console. */ > +       if (early_console == &early_vga_console && > +           boot_params.screen_info.orig_video_isVGA != 1) > +               early_console = NULL; > + >        return 0; >  } And assign null console as the last console as a fallback ? Regards Bastien