linux-kernel - Re: [PATCH v3] fbdev: ignore VESA modes if framebuffer does not support them

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Date:	Thu, 2 Oct 2008 23:40:11 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	spock@...too.org
Cc:	linux-kernel@...r.kernel.org,
	linux-fbdev-devel@...ts.sourceforge.net, krzysztof.h1@...zta.fm,
	bonbons@...ux-vserver.org, hpa@...or.com
Subject: Re: [PATCH v3] fbdev: ignore VESA modes if framebuffer does not
 support them

On Sun, 28 Sep 2008 14:54:15 +0200 Michal Januszewski <spock@...too.org> wrote:

> Currently, it is possible to set a graphics VESA mode at boot time via
> the vga= parameter even when no framebuffer driver supporting this is
> configured.  This could lead to the system booting with a black screen,
> without a usable console.
> 
> Fix this problem by only allowing to set graphics modes at boot time
> if a supporting framebuffer driver is configured.
> 
> Signed-off-by: Michal Januszewski <spock@...too.org>
> Acked-by: Krzysztof Helt <krzysztof.h1@...pl>
> ---
> This version of the patch replaces the FB_SUPPORTS_BOOT_VESA macro from
> screen-info.h with a config option in drivers/video/Kconfig.
> 
> diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
> index 401ad99..47e5080 100644
> --- a/arch/x86/boot/video-vesa.c
> +++ b/arch/x86/boot/video-vesa.c
> @@ -88,14 +88,11 @@ static int vesa_probe(void)
>  			   (vminfo.memory_layout == 4 ||
>  			    vminfo.memory_layout == 6) &&
>  			   vminfo.memory_planes == 1) {
> -#ifdef CONFIG_FB
> +#ifdef CONFIG_FB_BOOT_VESA_SUPPORT
>  			/* Graphics mode, color, linear frame buffer
>  			   supported.  Only register the mode if
>  			   if framebuffer is configured, however,
> -			   otherwise the user will be left without a screen.
> -			   We don't require CONFIG_FB_VESA, however, since
> -			   some of the other framebuffer drivers can use
> -			   this mode-setting, too. */
> +			   otherwise the user will be left without a screen. */
>  			mi = GET_HEAP(struct mode_info, 1);
>  			mi->mode = mode + VIDEO_FIRST_VESA;
>  			mi->depth = vminfo.bpp;
> @@ -133,10 +130,12 @@ static int vesa_set_mode(struct mode_info *mode)
>  	if ((vminfo.mode_attr & 0x15) == 0x05) {
>  		/* It's a supported text mode */
>  		is_graphic = 0;
> +#ifdef CONFIG_FB_BOOT_VESA_SUPPORT
>  	} else if ((vminfo.mode_attr & 0x99) == 0x99) {
>  		/* It's a graphics mode with linear frame buffer */
>  		is_graphic = 1;
>  		vesa_mode |= 0x4000; /* Request linear frame buffer */
> +#endif
>  	} else {
>  		return -1;	/* Invalid mode */
>  	}
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 70d135e..651249d 100644
> --- a/drivers/video/Kconfig
> +++ b/drivers/video/Kconfig
> @@ -76,6 +76,14 @@ config FB_DDC
>         select I2C
>         default n
>  
> +config FB_BOOT_VESA_SUPPORT
> +	bool
> +	depends on FB
> +	default n
> +	---help---
> +	  If true, at least one selected framebuffer driver can take advantage
> +	  of VESA video modes set at an early boot stage via the vga= parameter.
> +
>  config FB_CFB_FILLRECT
>  	tristate
>  	depends on FB
> @@ -679,6 +687,7 @@ config FB_VESA
>  	select FB_CFB_COPYAREA
>  	select FB_CFB_IMAGEBLIT
>  	select VIDEO_SELECT
> +	select FB_BOOT_VESA_SUPPORT
>  	help
>  	  This is the frame buffer device driver for generic VESA 2.0
>  	  compliant graphic cards. The older VESA 1.2 cards are not supported.
> @@ -702,6 +711,7 @@ config FB_IMAC
>  	select FB_CFB_FILLRECT
>  	select FB_CFB_COPYAREA
>  	select FB_CFB_IMAGEBLIT
> +	select FB_BOOT_VESA_SUPPORT
>  	help
>  	  This is the frame buffer device driver for the Intel-based Macintosh
>  
> @@ -1124,6 +1134,7 @@ config FB_INTEL
>  	select FB_CFB_FILLRECT
>  	select FB_CFB_COPYAREA
>  	select FB_CFB_IMAGEBLIT
> +	select FB_BOOT_VESA_SUPPORT
>  	help
>  	  This driver supports the on-board graphics built in to the Intel
>            830M/845G/852GM/855GM/865G/915G/915GM/945G/945GM/965G/965GM chipsets.
> @@ -1476,6 +1487,7 @@ config FB_SIS
>  	select FB_CFB_FILLRECT
>  	select FB_CFB_COPYAREA
>  	select FB_CFB_IMAGEBLIT
> +	select FB_BOOT_VESA_SUPPORT
>  	help
>  	  This is the frame buffer device driver for the SiS 300, 315, 330
>  	  and 340 series as well as XGI V3XT, V5, V8, Z7 graphics chipsets.

-mm's efifb-imacfb-consolidation-hardware-support.patch removed FB_IMAC
and moved it into FB_EDD.  But your patch changes FB_IMAC and not
FB_EDD, so I don't know what needs to be done here.

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