multiboot2 vs. grub2 implementation

[jakllsch]

Hi,

In the course of actually trying to use the MultibootDraft, I've discovered
some places where the draft and the grub2 implementation differ.

 * Multiboot Information Tags
  * Start Tag
    The Draft says key is 0x0000, grub2 says 0x0001.
  * Boot Loader Name tag is different
    The Draft says 0x0001, grub2 says 0x0002.
  * Module/Kernel Tags
    These tags seem to have different keys and different data formats
    than the draft indicates.
  * Memory Map Tag
    Does not seem to be implemented.

Additionally, the word-length of the values does not seem consistent.
bit 17 of the flags does not seem to affect the word size used in the
Multiboot Information structure. 

The Operating System Image header's load_addr and entry_addr fields
do not seem to be recognized, even with bit 8 in the flags set.  But
I did use 64-bit values for the addresses, so this may be the same
as the issue in the preceding paragraph.


The entry physical address field is very useful to the kernel I'm
using, as the ELF64 entry address supplied by the kernel I'm working
with is the virtual address, not the physical address.
The load address information in the ELF64 kernel I have are presently
also virtual addresses though this could/should probably be
changed in the linker script.  The kernel command line,
as well as the memory map are also useful tags for this x86_64 kernel.


        Jonathan Kollasch

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