[LinuxBIOS] New LAR access functions

Peter Stuge peter at stuge.se
Thu Jul 12 19:25:06 CEST 2007

On Thu, Jul 12, 2007 at 07:00:44PM +0200, Stefan Reinauer wrote:
> > > I agree. That's why lar should know about flash chip sector sizes.
> > 
> > This is probably best - lar is best suited for doing the math and
> Actually both lar and flashrom should be able to read flash chip
> description files.

Re these files, I desperately want a fallback so that something
intelligent can be done also without any flash description files.
Again single/many deliverables/components. Copying those small files
around can be a huge hassle. I would love to compile the latest list
available into the binary at build time, and allow a newer text file
to override it at run time. (Maybe even replace in the binary with
ELF tricks? :)

> Sectors might have different sizes. Not sure whether this
> "assymetrical" concept will be kept up in the future. Many modern
> chips are "symmetrical", ie have all equal sized blocks.

Hard to say. Sharing of single flash chips between multiple readers
on a single board supports having varying sector sizes, but lower
cost probably supports uniform sector sizes. OTOH flash may be so
cheap anyway that the little extra cost for varying sector sizes win.

I like the varying sector sizes a lot because it means we can use the
flash as NV storage in more ways, and I think we need the space.

> It would be nice if flashrom knows how to flash a part of a lar. ie
> "only normal, not fallback"

Definately a worthwhile goal!

> But 90% of flashrom's flash chip drivers dont know how to do that,
> and it would be quite some redesign to change it.

At least they know about sectors and page sizes already.

> > > One file is no file, two files are two files too many. ;)
> > 
> > I completely agree.  Its always best to only have a single
> > deliverable.
> It should be viable to flash "everything but the bootblock" in lar.

Good idea! It should even be the default. If flashrom detects that
the boot block sector already has an LB bootblock it doesn't
erase/flash it unless explicitly told to do so.

Note this means the bootblock eats up 64kb of SST49LF080A chips.
Plenty of room for serial recovery yay. :)

> But for deployment a complete image is what we really want. The
> fact that the bootblock is part of the lar is just artificial to
> make the handling nicer.



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