[openbeos] Re: Stage 1 Bootloader

  • From: "Axel Dörfler" <axeld@xxxxxxxxxxxxxxxx>
  • To: openbeos@xxxxxxxxxxxxx
  • Date: Mon, 25 Nov 2002 23:38:47 +0100 CET

Eike Dehling <e.e.dehling@xxxxxxxxxxxxxxxxxx> wrote:
> Ok. So it's at least a little more intelligent than some standard 
> blocklist 
> loader :)

Sure - and it's very flexible, too :-)

> Grub does have support for about 5 or 10 different filesystems, so 
> there 
> are enough examples to look at when implementing BFS.

Well, as I said, I won't do this.

> Also it can load with blocklists instead of from a filesystem, so it 
> could 
> already now load zbeos (maybe not pass parameters in the correct way 
> ...) 

Theoretically, it could, yes.

> But i don't see where your lack of real mode compilers comes from ... 
> borlands turbo C (available for free from the borland museum), MS 
> quick C 
> (still commercial i guess) are just some examples. of course they are 
> DOS 
> programs ... Although making it in assembly is probably easier since 
> compilers tend to make rather big code, and 800 bytes is not very 
> much.

Anyway, thanks for the hint, we might make some use out of it (I 
haven't spend time searching for them, yet :-).

> >I will have a closer look at the multiboot standard before defining 
> > the
> >protocol between stage 2 and the kernel. If it's not too much work, 
> > I
> >would try to be compliant, just to not have to change the protocol
> >again in the forseeable future.
> It is actually quite simple: your code is loaded in 32 bit mode with 
> linear 
> 4gig segements and a20 enabled.
> The code should be in a.out (requires a multiboot structure somewhere 
> in 
> the code) or in elf.
> You get passed a pointer to a structure with parameters in one of the 
> registers. (memory map, command line, loaded modules, etc.)

Well, as I said, I will have a look at it. If it is very similar to 
what we need and want to have, I will make it compliant, but I (myself) 
won't spend any time at improving GRUB to be able to load from a BFS 
Which means that you'd have to copy the files needed to a special 
partition that GRUB can access, too, to boot with it, if you don't want 
to use our stage 2 boot loader. Anyway, being multiboot compliant (even 
if we are) won't mean that you can boot with GRUB the same way as with 
the native loader. BFS is one reason, the driver settings are another, 
and there might even be more.


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