[PATCH] Video mode fixes in linux loader

[Pavel Roskin]

Hello!

This is an attempt to fix all issues with the video mode handling in the
new Linux loader.

First of all, free_page() doesn't belong to grub_linux_unload().  The
later function is called after the new kernel has been loaded, just
before the boot.  Thus it obliterates the data set up by the last
"linux" command if the previous Linux boot failed.

Instead, free_page() should be called from allocate_pages() to reset not
only real_mode_mem and prot_mode_mem, but also initrd_mem.

Next problem is that grub_linux_boot() can access linux_vesafb_modes
with a wrong index.  I believe we should threat modes that don't fit the
array as text modes.

I introduced GRUB_LINUX_VID_MODE_VESA_START for the first VESA mode we
support.  Also, I introduced a macro ARRAY_SIZE to calculate the array
size.

The default VGA mode is now GRUB_LINUX_VID_MODE_NORMAL, not the mode of
the kernel we tried to load before.  Finally, "vga=ask" is now
recognized.

ChangeLog:

        * include/grub/misc.h (ARRAY_SIZE): New macro.
        * include/grub/i386/linux.h (GRUB_LINUX_VID_MODE_VESA_START):
        New macro.
        * loader/i386/linux.c (allocate_pages): Use free_pages().
        (grub_linux_unload): Don't use free_pages().
        (grub_linux_boot): Prevent accessing linux_vesafb_modes with a
        wrong index.  Treat all other modes as text modes.
        (grub_cmd_linux): Initialize vid_mode unconditionally to
        GRUB_LINUX_VID_MODE_NORMAL.  Recognize and support "vga=ask".
        
Index: include/grub/misc.h
===================================================================
--- include/grub/misc.h (revision 2068)
+++ include/grub/misc.h (working copy)
@@ -26,6 +26,7 @@
 #include <grub/err.h>
 
 #define ALIGN_UP(addr, align) (((grub_uint64_t)addr + align - 1) & ~(align - 
1))
+#define ARRAY_SIZE(array) (sizeof (array) / sizeof (array[0]))
 
 #define grub_dprintf(condition, fmt, args...) grub_real_dprintf(__FILE__, 
__LINE__, condition, fmt, ## args);
 /* XXX: If grub_memmove is too slow, we must implement grub_memcpy.  */
Index: include/grub/i386/linux.h
===================================================================
--- include/grub/i386/linux.h   (revision 2068)
+++ include/grub/i386/linux.h   (working copy)
@@ -38,6 +38,7 @@
 #define GRUB_LINUX_VID_MODE_NORMAL     0xFFFF
 #define GRUB_LINUX_VID_MODE_EXTENDED   0xFFFE
 #define GRUB_LINUX_VID_MODE_ASK                0xFFFD
+#define GRUB_LINUX_VID_MODE_VESA_START 0x0301
 
 #define GRUB_LINUX_SETUP_MOVE_SIZE     0x9100
 #define GRUB_LINUX_CL_MAGIC            0xA33F
Index: loader/i386/linux.c
===================================================================
--- loader/i386/linux.c (revision 2068)
+++ loader/i386/linux.c (working copy)
@@ -206,8 +206,7 @@ allocate_pages (grub_size_t prot_size)
   prot_mode_pages = (prot_size >> 12);
   
   /* Initialize the memory pointers with NULL for convenience.  */
-  real_mode_mem = 0;
-  prot_mode_mem = 0;
+  free_pages();
   
   /* FIXME: Should request low memory from the heap when this feature is
      implemented.  */
@@ -332,7 +331,9 @@ grub_linux_boot (void)
   
   params = real_mode_mem;
 
-  if (vid_mode == GRUB_LINUX_VID_MODE_NORMAL || vid_mode == 
GRUB_LINUX_VID_MODE_EXTENDED)
+  if (vid_mode < GRUB_LINUX_VID_MODE_VESA_START ||
+      vid_mode >= GRUB_LINUX_VID_MODE_VESA_START +
+                 ARRAY_SIZE (linux_vesafb_modes))
     grub_video_restore ();
   else if (vid_mode)
     {
@@ -340,7 +341,7 @@ grub_linux_boot (void)
       int depth, flags;
       
       flags = 0;
-      linux_mode = &linux_vesafb_modes[vid_mode - 0x301];
+      linux_mode = &linux_vesafb_modes[vid_mode - 
GRUB_LINUX_VID_MODE_VESA_START];
       depth = linux_mode->depth;
       
       /* If we have 8 or less bits, then assume that it is indexed color mode. 
 */
@@ -443,7 +444,6 @@ grub_linux_boot (void)
 static grub_err_t
 grub_linux_unload (void)
 {
-  free_pages ();
   grub_dl_unref (my_mod);
   loaded = 0;
   return GRUB_ERR_NONE;
@@ -570,6 +570,7 @@ grub_cmd_linux (grub_command_t cmd __att
               (unsigned) real_size, (unsigned) prot_size);
 
   /* Detect explicitly specified memory size, if any.  */
+  vid_mode = GRUB_LINUX_VID_MODE_NORMAL;
   linux_mem_size = 0;
   for (i = 1; i < argc; i++)
     if (grub_memcmp (argv[i], "vga=", 4) == 0)
@@ -581,6 +582,8 @@ grub_cmd_linux (grub_command_t cmd __att
          vid_mode = GRUB_LINUX_VID_MODE_NORMAL;
        else if (grub_strcmp (val, "ext") == 0)
          vid_mode = GRUB_LINUX_VID_MODE_EXTENDED;
+       else if (grub_strcmp (val, "ask") == 0)
+         vid_mode = GRUB_LINUX_VID_MODE_ASK;
        else
          vid_mode = (grub_uint16_t) grub_strtoul (val, 0, 0);
 


-- 
Regards,
Pavel Roskin