linux-kernel - Re: [PATCH][RESEND] x86: Do not write to VGA memory space if CONFIG_VGA

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Message-ID: <84144f021003310832i3420e4c1g7396b4d1f311f393@mail.gmail.com>
Date:	Wed, 31 Mar 2010 17:32:03 +0200
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Guenter Roeck <guenter.roeck@...csson.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...hat.com,
	x86 maintainers <x86@...nel.org>
Subject: Re: [PATCH][RESEND] x86: Do not write to VGA memory space if 
	CONFIG_VGA_CONSOLE is undefined

On Wed, Mar 31, 2010 at 4:41 PM, Guenter Roeck
<guenter.roeck@...csson.com> wrote:
> Current early_printk code writes into VGA memory space even
> if CONFIG_VGA_CONSOLE is undefined. This can cause problems
> if there is no VGA device in the system, especially if the memory
> is used by another device.
>
> Fix problem by redirecting output to early_serial_console
> if CONFIG_VGA_CONSOLE is undefined.
>
> Signed-off-by: Guenter Roeck <guenter.roeck@...csson.com>

Reviewed-by: Pekka Enberg <penberg@...helsinki.fi>

> ---
> Sorry if you have seen this before. I seem to have trouble with our mailer.
>
>  arch/x86/kernel/early_printk.c |   12 ++++++++++--
>  1 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
> index b9c830c..1942039 100644
> --- a/arch/x86/kernel/early_printk.c
> +++ b/arch/x86/kernel/early_printk.c
> @@ -160,8 +160,16 @@ static struct console early_serial_console = {
>        .index =        -1,
>  };
>
> +#ifdef CONFIG_VGA_CONSOLE
> +#define EARLY_CONSOLE  early_vga_console
> +static const int have_vga_console = 1;
> +#else
> +#define EARLY_CONSOLE  early_serial_console
> +static const int have_vga_console;
> +#endif
> +
>  /* Direct interface for emergencies */
> -static struct console *early_console = &early_vga_console;
> +static struct console *early_console = &EARLY_CONSOLE;
>  static int __initdata early_console_initialized;
>
>  asmlinkage void early_printk(const char *fmt, ...)
> @@ -216,7 +224,7 @@ static int __init setup_early_printk(char *buf)
>                        early_serial_init(buf + 4);
>                        early_console_register(&early_serial_console, keep);
>                }
> -               if (!strncmp(buf, "vga", 3) &&
> +               if (have_vga_console && !strncmp(buf, "vga", 3) &&
>                    boot_params.screen_info.orig_video_isVGA == 1) {
>                        max_xpos = boot_params.screen_info.orig_video_cols;
>                        max_ypos = boot_params.screen_info.orig_video_lines;
> --
> 1.7.0.87.g0901d
>
> --
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