multiboot2

[phcoder <phcoder@gmail.com>]

Hello I was looking into multiboot2 specifications and have some 
suggestions:
1) double the size of flags. 8 features per category seems to be few. it 
could even be made completely expandable by the following format:
<magic>
<number of flag dwords>
<dword1 as defined in current draft>
<dword2 as defined in current draft, next packet of flags>
...
<checksum>
2) "All undefined flags *should* be set to zero for future use. "
IMO in this place all OSes should be required to follow this rule in 
current terminology it would be "must"
3) "The physical address to which the boot loader should jump in order 
to start running the operating system."
In current terminology should make no real sense here
4) "This tag should contain a string that enables operating systems to 
distinguish between different bootloaders and different versions of the 
same bootloader."
Parsing strings may be difficult. Perhaps we could include a version tag 
with a format dependent on bootloader and optionally a requirement that 
higher numbers are newer versions?
5)memory map: "The order of memory maps is not guaranteed but a boot 
loader should sort the items based on the starting addresses. "
I don't like the optionality of this rule if it's included in 
specifications it should be either required or dropped altogether. 
Otherwise we risk to have OSes which rely on sorting and bootloaders 
which doesn't sort. I'm personally for making it mandatory for reasons 
similar to next entry
6) memory map. "<!> Tags of this type should be omitted on architectures 
where the OS is able to retrieve this information from firmware. (Doing 
do will encourage OS portability across bootloaders, and simplify GRUB 
development and maintenance.) "
This contradicts the goal of easier OS developement and may result in 
semi-compatible OS and bootloaders. Additionally I think that 
eliminating the necessity of use of firmware from OS is a good thing and 
allows easier porting between architectures differing only by firmware
7) Command line tag. I propose to reserve the identifier 0x0005 for 
command line and make it the same format as "Boot Loader Name" but 
arguments shouldn't include kernel image name. This way we would prevent 
OSes from trying to access this file by bootloader-specific name. In 
addition in both "Boot Loader Name" and "Command-line" we should specify 
the encoding to be utf-8


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Regards
Vladimir 'phcoder' Serbinenko