Add alignment requirements

doc/kernel.c

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <multiboot2.h>
+#include "multiboot2.h"
 
 /* Macros.  */
 
@@ -62,11 +62,18 @@ cmain (unsigned long magic, unsigned long addr)
       return;
     }
 
+  if (addr & 7)
+    {
+      printf ("Unaligned mbi: 0x%x\n", addr);
+      return;
+    }
+
   size = *(unsigned *) addr;
   printf ("Announced mbi size 0x%x\n", size);
-  for (tag = (struct multiboot_tag *) (addr + 4);
+  for (tag = (struct multiboot_tag *) (addr + 8);
        tag->type != MULTIBOOT_TAG_TYPE_END;
-       tag = (struct multiboot_tag *) ((multiboot_uint8_t *) tag + tag->size))
+       tag = (struct multiboot_tag *) ((multiboot_uint8_t *) tag 
+				       + ((tag->size + 7) & ~7)))
     {
       printf ("Tag 0x%x, Size 0x%x\n", tag->type, tag->size);
       switch (tag->type)
@@ -105,12 +112,11 @@ cmain (unsigned long magic, unsigned long addr)
 	    for (mmap = ((struct multiboot_tag_mmap *) tag)->entries;
 		 (multiboot_uint8_t *) mmap 
 		   < (multiboot_uint8_t *) tag + tag->size;
-		 mmap = (multiboot_memory_map_t *) ((unsigned long) mmap
+		 mmap = (multiboot_memory_map_t *) 
-						    + mmap->size
+		   ((unsigned long) mmap
-						    + sizeof (mmap->size)))
+		    + ((struct multiboot_tag_mmap *) tag)->entry_size))
-	      printf (" size = 0x%x, base_addr = 0x%x%x,"
+	      printf (" base_addr = 0x%x%x,"
 		      " length = 0x%x%x, type = 0x%x\n",
-		      (unsigned) mmap->size,
 		      (unsigned) (mmap->addr >> 32),
 		      (unsigned) (mmap->addr & 0xffffffff),
 		      (unsigned) (mmap->len >> 32),
@@ -209,7 +215,8 @@ cmain (unsigned long magic, unsigned long addr)
 
 	}
     }
-  tag = (struct multiboot_tag *) ((multiboot_uint8_t *) tag + tag->size);
+  tag = (struct multiboot_tag *) ((multiboot_uint8_t *) tag 
+				  + ((tag->size + 7) & ~7));
   printf ("Total mbi size 0x%x\n", (unsigned) tag - addr);
 }    
 

doc/multiboot.texi

@@ -594,11 +594,12 @@ operating system's responsibility to avoid overwriting this memory until
 it is done using it.
 
 @subsection Basic tags structure
-Boot information consists of fixed part and a series of tags. Fixed part is as following:
+Boot information consists of fixed part and a series of tags. Its start is 8-bytes aligned.  Fixed part is as following:
 @example
 @group
         +-------------------+
 0-3     | total_size        |
+4-7     | reserved          |
         +-------------------+
 @end group
 @end example
@@ -606,6 +607,8 @@ Boot information consists of fixed part and a series of tags. Fixed part is as f
 @samp{total_size} contains the total size of boot information including
 this field and terminating tag in bytes
 
+@samp{reserved} is always set to zero and must be ignored by OS image
+
 Every tag begins with following fields:
 
 @example
@@ -618,8 +621,8 @@ Every tag begins with following fields:
 @end example
 
 @samp{type} contains an identifier of contents of the rest of the tag.
-@samp{size} contains the size of tag including header fields.
+@samp{size} contains the size of tag including header fields but not including padding.
-Tags follow one another without any gaps. Tags are terminated by a tag of type @samp{0} and size @samp{8}.
+Tags follow one another padded when necessary in order for each tag to start at 8-bytes aligned address. Tags are terminated by a tag of type @samp{0} and size @samp{8}.
 
 @subsection Basic memory information
 @example
@@ -695,8 +698,8 @@ partition on a disk partitioned in conventional DOS style, then
 @end group
 @end example
 
-@samp{string} contains command line. The command line is a normal C-styl 
+@samp{string} contains command line. The command line is a normal C-style 
-zero-terminated UTF-8 string padded to have length divisible by 4.
+zero-terminated UTF-8 string.
 
 @subsection Modules
 @example
@@ -723,8 +726,6 @@ modules as executable programs), or a pathname (e.g. if the operating
 system treats boot modules as files in a file system), but its exact use
 is specific to the operating system. 
 
-Tag is padded in the way to have size divisible by 4.
-
 One tag appears per module. This tag type may appear multiple times.
 
 @subsection ELF-Symbols
@@ -754,53 +755,46 @@ the sections are in memory (refer to the i386 @sc{elf} documentation for
 details as to how to read the section header(s)).
 
 @subsection Memory map
-If bit 6 in the @samp{flags} word is set, then the @samp{mmap_*} fields
-are valid, and indicate the address and length of a buffer containing a
-memory map of the machine provided by the @sc{bios}. @samp{mmap_addr} is
-the address, and @samp{mmap_length} is the total size of the buffer. The
-buffer consists of one or more of the following size/structure pairs
-(@samp{size} is really used for skipping to the next pair):
 
-@example
+This tag provides memory map.
-@group
-        +-------------------+
--4      | size              |
-        +-------------------+
-0       | base_addr         |
-8       | length            |
-16      | type              |
-        +-------------------+
-@end group
-@end example
 
-where @samp{size} is the size of the associated structure in bytes, which
-can be greater than the minimum of 20 bytes. @samp{base_addr} is the
-starting address. @samp{length} is the size of the memory region in bytes.
-@samp{type} is the variety of address range represented, where a
-value of 1 indicates available @sc{ram}, and all other values currently
-indicated a reserved area.
-
-The map provided is guaranteed to list all standard @sc{ram} that should
-be available for normal use.
-
-The corresponding tag is
 @example
 @group
         +-------------------+
 0       | type = 6          |
 4       | size              |
-8-xx    | entries           |
+8       | entry_size        |
+12      | entry_version     |
+16-xx   | entries           |
         +-------------------+
 @end group
 @end example
 
-@subsection Boot loader name
+@samp{entry_size} contains the size of one entry so that in future new fields may be added to it. It's guaranteed to be a multiple of 8. @samp{entry_version} is currently set at @samp{0}. Future versions will increment this field. Future version are guranteed to be backward compatible with older format. Each entry has the following structure:
-If bit 9 in the @samp{flags} is set, the @samp{boot_loader_name} field
-is valid, and contains the physical address of the name of a boot
-loader booting the kernel. The name is a normal C-style zero-terminated
-string.
 
-Corresponding tag is:
+
+@example
+@group
+        +-------------------+
+0       | base_addr         |
+8       | length            |
+16      | type              |
+20      | reserved          |
+        +-------------------+
+@end group
+@end example
+
+@samp{size} contains the size of current entry including this field itself. It may be bigger than 24 bytes in future versions but is guaranteed to be
+@samp{base_addr} is the starting physical address. @samp{length} is the size of the memory region in bytes.
+@samp{type} is the variety of address range represented, where a
+value of 1 indicates available @sc{ram}, and all other values currently
+indicated a reserved area.
+@samp{reserved} is set to @samp{0} by bootloader and must be ignored by the OS image.
+
+The map provided is guaranteed to list all standard @sc{ram} that should
+be available for normal use.
+
+@subsection Boot loader name
 @example
 @group
         +-------------------+
@@ -811,7 +805,9 @@ Corresponding tag is:
 @end group
 @end example
 
-@samp{string} contains zero-terminated UTF-8 string padded to have length divisible by 4.
+@samp{string} contains  the name of a boot
+loader booting the kernel. The name is a normal C-style UTF-8 zero-terminated
+string.
 
 @subsection APM table
 The tag type 10 contains @sc{apm} table
@@ -819,7 +815,7 @@ The tag type 10 contains @sc{apm} table
 @group
         +----------------------+
 0       | type = 10            |
-4       | size                 |
+4       | size = 28            |
 8       | version              |
 10      | cseg                 |
 12      | offset               |
@@ -889,17 +885,18 @@ yourself.
 24      | framebuffer_height |
 28      | framebuffer_bpp    |
 29      | framebuffer_type   |
-30      | color_info         |
+30      | reserved           |
+32      | color_info         |
         +--------------------+
 @end group
 @end example
 
-The field @samp{framebuffer_addr} contains framebuffer physical address. This field is 64-bit wide but bootloader @dfn{should} set it under 4GiB if possible for compatibility with payloads which aren't aware of PAE or amd64. The field @samp{framebuffer_pitch} contains pitch in bytes. The fields @samp{framebuffer_width}, @samp{framebuffer_height} contain framebuffer dimensions in pixels. The field @samp{framebuffer_bpp} contains number of bits per pixel. If @samp{framebuffer_type} is set to 0 it means indexed color. In this case color_info is defined as follows:
+The field @samp{framebuffer_addr} contains framebuffer physical address. This field is 64-bit wide but bootloader @dfn{should} set it under 4GiB if possible for compatibility with payloads which aren't aware of PAE or amd64. The field @samp{framebuffer_pitch} contains pitch in bytes. The fields @samp{framebuffer_width}, @samp{framebuffer_height} contain framebuffer dimensions in pixels. The field @samp{framebuffer_bpp} contains number of bits per pixel. @samp{reserved} always contains 0 in current version of specification and must be ignored by OS image. If @samp{framebuffer_type} is set to 0 it means indexed color. In this case color_info is defined as follows:
 @example
 @group
         +----------------------------------+
-30      | framebuffer_palette_num_colors   |
+32      | framebuffer_palette_num_colors   |
-34-xx   | framebuffer_palette              |
+36-xx   | framebuffer_palette              |
         +----------------------------------+
 @end group
 @end example
@@ -920,12 +917,12 @@ Then color_type is defined as follows:
 @example
 @group
        +----------------------------------+
-30     | framebuffer_red_field_position   |
+32     | framebuffer_red_field_position   |
-31     | framebuffer_red_mask_size        |
+33     | framebuffer_red_mask_size        |
-32     | framebuffer_green_field_position |
+34     | framebuffer_green_field_position |
-33     | framebuffer_green_mask_size      |
+35     | framebuffer_green_mask_size      |
-34     | framebuffer_blue_field_position  |
+36     | framebuffer_blue_field_position  |
-35-35  | framebuffer_blue_mask_size       |
+37-37  | framebuffer_blue_mask_size       |
        +----------------------------------+
 @end group
 @end example

doc/multiboot2.h

@@ -51,6 +51,7 @@
 /* This flag indicates the use of the address fields in the header.  */
 #define MULTIBOOT_AOUT_KLUDGE			0x00010000
 
+#define MULTIBOOT_TAG_ALIGN                  8
 #define MULTIBOOT_TAG_TYPE_END               0
 #define MULTIBOOT_TAG_TYPE_CMDLINE           1
 #define MULTIBOOT_TAG_TYPE_BOOT_LOADER_NAME  2
@@ -60,8 +61,6 @@
 #define MULTIBOOT_TAG_TYPE_MMAP              6
 #define MULTIBOOT_TAG_TYPE_VBE               7
 #define MULTIBOOT_TAG_TYPE_FRAMEBUFFER       8
-#define MULTIBOOT_TAG_TYPE_ELF_SECTIONS      9
-#define MULTIBOOT_TAG_TYPE_APM              10
 
 #ifndef ASM_FILE
 
@@ -104,12 +103,14 @@ struct multiboot_color
 
 struct multiboot_mmap_entry
 {
-  multiboot_uint32_t size;
   multiboot_uint64_t addr;
   multiboot_uint64_t len;
 #define MULTIBOOT_MEMORY_AVAILABLE		1
 #define MULTIBOOT_MEMORY_RESERVED		2
+#define MULTIBOOT_MEMORY_ACPI_RECLAIMABLE       3
+#define MULTIBOOT_MEMORY_NVS                    4
   multiboot_uint32_t type;
+  multiboot_uint32_t zero;
 } __attribute__((packed));
 typedef struct multiboot_mmap_entry multiboot_memory_map_t;
 
@@ -123,6 +124,8 @@ struct multiboot_tag_string
 {
   multiboot_uint32_t type;
   multiboot_uint32_t size;
+  multiboot_uint32_t entry_size;
+  multiboot_uint32_t entry_version;
   char string[0];
 };
 
@@ -156,6 +159,8 @@ struct multiboot_tag_mmap
 {
   multiboot_uint32_t type;
   multiboot_uint32_t size;
+  multiboot_uint32_t entry_size;
+  multiboot_uint32_t entry_version;
   struct multiboot_mmap_entry entries[0];  
 };
 
@@ -197,6 +202,7 @@ struct multiboot_tag_framebuffer_common
 #define MULTIBOOT_FRAMEBUFFER_TYPE_RGB     1
 #define MULTIBOOT_FRAMEBUFFER_TYPE_EGA_TEXT	2
   multiboot_uint8_t framebuffer_type;
+  multiboot_uint16_t reserved;
 };
 
 struct multiboot_tag_framebuffer

doc/src2texi

@@ -10,7 +10,7 @@ texi=`basename $3`
 
 sed -e 's,[{}],@&,g'					\
     -e 's,/\*\(@.*\)\*/,\1,g'				\
-    -e 's,/\*  *,/* @r{,g' -e 's,  *\*/,} */,'		\
+    -e 's,/\*,/* @r{,g' -e 's,  *\*/,} */,'		\
     -e 's/\(@[a-z][a-z]*\)@{\([^}]*\)@}/\1{\2}/g'	\
     ${dir}/${src} | expand > ${texi}.new
 mv -f ${texi}.new ${dir}/${texi}