Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753669Ab0DZQQB (ORCPT ); Mon, 26 Apr 2010 12:16:01 -0400 Received: from imr1.ericy.com ([198.24.6.9]:49931 "EHLO imr1.ericy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752989Ab0DZQP7 (ORCPT ); Mon, 26 Apr 2010 12:15:59 -0400 Date: Mon, 26 Apr 2010 09:11:20 -0700 From: Guenter Roeck To: Bastien ROUCARIES CC: "linux-kernel@vger.kernel.org" , "penberg@cs.helsinki.fi" , "mingo@redhat.com" , "x86@kernel.org" Subject: Re: [PATCH v3] x86: Do not write into VGA memory space if there is no VGA device in the system Message-ID: <20100426161120.GA18509@ericsson.com> References: <1271780217-27472-1-git-send-email-guenter.roeck@ericsson.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2528 Lines: 64 On Mon, Apr 26, 2010 at 11:43:44AM -0400, Bastien ROUCARIES wrote: > 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 ? > Sounds good to me. Peter, would that get your approval ? Guenter -- 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/