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: Michal Januszewski <spock@gentoo.org>
Acked-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index 1e6fe0214c85..99b3079dc6ab 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 */
         }