Re: SILO/GRUB coordination

[Ben Collins]

On Thu, May 03, 2001 at 10:24:55AM -0600, Gordon Matzigkeit wrote:
>  BC> SILO's stage one loader merely sets up the system so it can
>  BC> execute a second stage loader (it has a stage1 loader for sparc
>  BC> and sparc64). So it should be able to execute any sparc code as
>  BC> the second stage loader, assuming it fits into the 512k(?) that
>  BC> is allowed.
> 
> That's essentially the same role that GRUB's stage1 has: to make up
> for arbitrary limitations in what the BIOS/monitor can load itself.
> The PC stage1 has to fit in under 380 bytes, which is enough code to
> load the stage2 from floppy or hard disk, using LBA mode if necessary.
> 
> That all works in such a tiny space using some creative assembly
> hacking done by Okuji and others.  Maybe there's a way to merge the
> sparc and sparc 64 stage1s (or maybe not, I don't know how different
> the architectures are)?

Basically the same idea, although merging sparc/sparc64 is not possible
that I know of.

>  BC> I'd say it is worth looking in to. Also note that sparc doesn't
>  BC> have the same type of initial terminal as PC's, so that has to be
>  BC> taken into account. At the second stage loader, it will only have
>  BC> the black and white text console.
> 
> We have a similar constraint when working from serial console.
> Currently we assume vt100 terminal capability, but there has been some
> discussion about making a separate dumb-terminal UI as a fallback for,
> say, teletypes. ;)

That's good to know. SPARC can have a serial console as it's BIOS
console (supported by the hardware).

I'll be glad to look into whatever anyone else has in mind. Honestly,
I'm in no position to author any such code. I'm more of a middle man,
approving what needs to be in the SILO code itself. I'd really like to
keep SILO core around for a minimum boot loader (much like LILO will
always remain), and allow anyone who wants to use the SILO code to
create SPARC support in grub.

Ben

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