[coreboot] cbfs XIP patch

ron minnich rminnich at gmail.com
Tue May 5 17:06:41 CEST 2009

On Tue, May 5, 2009 at 5:29 AM, Myles Watson <mylesgw at gmail.com> wrote:

> Someone needs to fix remove then.  Right now it moves all entries after it
> and zeroes the new space.  I guess most of my confusion came from the
> implementation/design gap.

I think it was my confusion, not yours :-)

But I think we have to have clean support for XIP in ROM, which means
we have to have a way for cbfs to place a block of code in a
designated place.
I like the idea of having the ROM stages visible in cbfs.

If we are certain we don't need XIP then we don't need this patch. But
if we have XIP we can
remove some fairly confusing __asm__ code in failover, as well as the
attendant load scripts.  Also, since the
stage header has the entry point as well, we get rid of the need to
have a reset vector at the end of the normal
and failover ROM images -- a much cleaner way to go.

Some suggestions:
- adopt a coarser granularity. Were we to adopt, e.g., 512B as a block
size, then at most the walking code would have to check  4096 items
on even a 2 Mbyte ROM (as opposed to the current 128K items)
- zero fill
- NEXT pointer

All of these will work.


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