Re: [PATCH] enable multiboot2 loader on i386-ieee1275

[Marco Gerards <mgerards@xs4all.nl>]

Robert Millan <rmh@aybabtu.com> writes:

> On Wed, Jan 23, 2008 at 11:38:48AM +0100, Marco Gerards wrote:
>> >> > Though I don't see why not do it.  The boot abi is already compatible on
>> >> > PowerPC:
>> >> >
>> >> >   http://grub.enbug.org/MultibootDraft#head-198f9346038a3782a8263de281dd9cf2eb2759a8
>> >> 
>> >> Do you suggest to change the interface for x86?
>> >
>> > Yes.  Multiboot2 is still a draft and not widely used (not even in comparison to
>> > Multiboot1).  I don't think it's a big problem to change this.
>> 
>> We could use ebx or so.  Or will this cause new problems?
>
> Well, EBX itself is being used for the MBI, so not a good choice ;-)
>
> About using a free register (I think ECX and EDX aren't used), this might
> cause the inconvenience that you might need to reestructure startup code, in
> case it is laid out in a way that already makes use of that register.

You can move it to EAX in case you do not care about OFW.  In that
case you get the old situation back.  In case of OFW the old situation
never worked :-)

> I don't think this is the case for the average OFW application that is written
> in C and just has a few lines of asm in _start.

Right.  And like I said, other kernels can just move ECX to EAX and
the old code can be used.

--
Marco