Re: [Linux-ia64] Re: [PATCH] head.S fix for unusual load addrs

[Jesse Barnes <jbarnes@sgi.com>]

On Wed, May 07, 2003 at 04:51:21PM -0700, David Mosberger wrote:
> Hi Tony,
> 
> Great summary!

Yeah, thanks.  It's a good outline of our options.

>   Tony> 3) David's suggestion of boot-time relocation.  Probably
>   Tony> simplest to implement this in elilo, but if you are really
>   Tony> good at PIC asm code it could be done in the kernel startup
>   Tony> sequence.
> 
> Agreed.  Anyone who's ever debugged the ld.so startup code will agree
> that it's much better to do the relocation in elilo.
> 
>   Tony>  pros) Just like linking kernel at a new address.  Avoids the
>   Tony> __tpa() issue.  Doesn't invalidate any assumptions about how
>   Tony> to get from virtual to physical addresses and back again.
> 
>   Tony>  cons) Nobody has implemented it.
> 
> I think:
> 
> 	- kernel text addresses vary depending on physical memory conf.
> 
> is potentially a bigger issue.  Implementing the relocator in elilo
> should be really easy (just take the kernel loader and massage it a
> bit).
> 
> How many tools are out there that depend on System.map or similar?  I
> suppose you could just generate a fresh System.map at boot time (or
> have something like /proc/System.map).

Ahh, this might be a good way to go.  We'd basically be relinking the
kernel at load time with a new KERNEL_START, right?  I haven't looked
at the new module loader code yet (in fact, I've never done any linker
stuff), but I will now.

Thanks,
Jesse