>>>>> +This is useful for example if you want to write only a part of the flash chip and leave everything else alone
>>>>> +without preparing an image of the complete chip manually:
>>>> Uhh... sounds denglish. Suggested rewording:
>>>> This allows replacing part of a ROM file with contents from another file
>>>> before writing the resulting contents to the flash chip, eliminating the
>>>> separate step of manually assembling a combined ROM image.
>>> You seem to imply that the -i parameters do only overwrite parts of the
>>> file given by -w. While this is true for the current implementation,
>>> David and I discussed about making the file parameter after -w
>>> optional.
>> Ouch! I think that is a really really bad idea. I can see reasons to
>> avoid full image files, but it feels wrong to have undefined regions in
>> the image. Especially if writing fails and recovery is needed.
> There is no such thing as an undefined region (yet at least). For
> address ranges for which no content is supplied by the user in the form
> of an <image file> or a <region file>, the old content of the flash
> chip is what should be there after any flashrom invocation. Cases of
> "-w -i bla" where neither an <image file> nor a <region file> are given
> need to be handled as errors of course.

That would make an implicit read from the flash chip before any write a
hard requirement. I hear people complaining from time to time about the
initial chip read in flashrom, and this won't make it better.

Besides that, writes where part of the image is read on-the-fly from the
flash chip directly before writing are not reproducible if an error
occurs. Think of the following scenario: Writing fails, and the flash
chip is now partially corrupted due to an erase command which affected a
larger region size than expected. As a result, parts of the implicitly
read region are now erased. Repeating the same write command with a
fixed flashrom version will _not_ yield the correct flash chip contents.
User despairs, smashes the computer and takes up a career in pottery. If
the image had been built completely from on-disk files (i.e. without
implicit chip reads), repeating the same write command would have
resulted in the correct flash chip contents.

> But anyway, your sentence still implies that the file given in -w is
> modified and that's what I was concerned about actually. No idea why I
> brought up the file-less -w at all (anymore) sorry.

I see. Not sure how to express that best. Next try:
This allows replacing the contents of one ROM image region with contents

from another file before writing the resulting contents to the flash
chip, eliminating the separate step of manually assembling a combined
ROM image.

There's another problem with the patch, though: Allowing region files

for read (instead of just for write) does violate the principle of least
surprise: Some users might expect regions to be written to separate
files on disk, i.e. having -r -i as reverse operation to -w -i. Right
now that assumption is not true.