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Commit 4d31a2b7 authored by Michal Januszewski's avatar Michal Januszewski Committed by Linus Torvalds
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fbdev: ignore VESA modes if framebuffer does not support them 



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: default avatarMichal Januszewski <spock@gentoo.org>
Acked-by: default avatarKrzysztof Helt <krzysztof.h1@wp.pl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5ab48409

arch/x86/boot/video-vesa.c

+4 −5
Original line number Diff line number Diff line
@@ -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 */

	}

drivers/video/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -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
@@ -681,6 +689,7 @@ config FB_VESA 
	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 generic VESA 2.0

	  compliant graphic cards. The older VESA 1.2 cards are not supported.
@@ -1117,6 +1126,7 @@ 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.
@@ -1469,6 +1479,7 @@ 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.