Re: Loading below 1 MB

[Viktor Pracht]

> I don't think that will be supported, unless someone sends a
> patch. Because:

I will eventually learn some more C and supply a patch, but don't expect
that in the next few years. Until then, somebody please remove that last
section from the Multiboot specification. Otherwise, people don't believe
that V2_OS is Multiboot compliant if GRUB is unable to load it.

> * That is not technically interesting.
> * You don't need to rely on a boot loader to load your OS image below
>   1MB, since you can relocate your OS image after being loaded.

The kernel image of V2_OS is loaded at 8000h and relocates its runtime part
to 500h anyway. It would be even not much work to make the initialization
part position-independent, so the kernel could be loaded at 8000h by the
Real Mode boot sector and at 1 MB by a Multiboot loader.

The reason for loading the image below 1 MB is keeping RAM requirement below
2 MB.

Low-memory systems that are mostly not 100% PC compatible (e. g. embedded,
handhelds) are one target of V2_OS. Such systems need preloaded modules for
their special hardware, which can't be loaded by the boot sector. If GRUB
requires the 1 MB load address then the RAM requirement of the kernel jumps
an order of magnitude (!) from 128 KB to 2 MB. And this requirement is the
same for low-memory systems. (No, the users should not be forced to compile
the kernel themselves before their system is usable, as with Linux ;-)


- VP