Many thanks for your report, this is what I found out:
11:14 <@Hellsenberg> tarzeau: ah, the nic flashers with parallel flash
chips don't always have all the address lines connected, which
effectively caps the maximum flash chip size.
11:15 < tarzeau> that means it's a bug always, or only sometimes? or
it's not a bug
11:16 <@Hellsenberg> that means it's a hardware limitation
11:16 <@Hellsenberg> (i.e. not a bug in flashrom)
11:17 <@Hellsenberg> also, flashrom warns about it for a good reason
11:17 < tarzeau> mind replying to the bug report?
11:19 <@Hellsenberg> not sure how I would reply, but feel free to use
this info to reply
Cheers,
