[coreboot] cbfs XIP patch

ron minnich rminnich at gmail.com
Tue May 5 17:33:14 CEST 2009

On Tue, May 5, 2009 at 8:26 AM, Patrick Georgi <patrick at georgi-clan.de> wrote:

> Consider the following case: The system has _two_ images it requires at
> fixed addresses right after another. We don't process these images (eg. EC
> firmware) ourselves, but have to take care that they're at the right spot
> (similar to your XIP stuff).
> We want to keep the images as two entries in cbfs (as they have different
> release cycles)
> The layout would look like this:
> file1-data | file2-data
> The current algorithm in coreboot and seabios says to walk the chain by
> taking the current cbfs_file address, adding the offset (so you're at the
> beginning of the file in question), and adding the file length (so you're at
> the first byte after the file in question). There, the current algorithm
> expects a new cbfs_file header.
> But there's already file2's data in the way. Oops.
> With the next field, we decouple the file location and the cbfs_file
> location completely. offset/len point to the file data, next points to the
> next header.

Thanks, I see it now.

So this scenario requires that we have two cbfs file headers, and data
somewhere else, not necessarily contiguous with the
header. Does the cbfstool currently create this kind of image?


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