[coreboot] flashrom image identification problem/coreboot signature RFC

Stefan Reinauer stepan at coresystems.de
Mon Jun 16 19:53:08 CEST 2008

Carl-Daniel Hailfinger wrote:

>> Top 256 bytes will not always work. The current trouble is due to the
>> fact that we have some mainboards that need the information in a
>> different place than others.
> Anything in the top 4k would be OK for me, unless there are specific
> reasons this is impossible with some boards. I'd appreciate a pointer
> about the "different place" thing.

Why would you want to artificially limit this at all. A lar entry can be
anywhere in the binary and it will still work. Now imagine how flexible
that would be ;-)

>> Other than that, we might indeed put the coreboot version into the
>> firmware signature, too, if there's a reason to do so. Is there?
> Not sure about svn revision, but differentiating between v2 and v3 would
> help. For one, we could keep a pseudo-LAR out of v2.
What's the benefit of using "CB20" as a magic rather than "LARCHIVE"?
Exactly: None.
There are disadvantages to having to maintain two different ways of
doing things though. Especially given that v2 is going to be obsoleted
some time.
>> I miss the actual information in your suggestion, namely the mainboard
>> vendor and type.
> Placing vendor and type somewhere else is possible, as long as flashrom
> knows that it should look there.
Sure. And this is what the whole discussion is about. Maybe you missed
the point in the first place?

>> Since we already have LAR, using that format instead of yet another
>> signature rule makes a lot of sense in my opinion.
> For v3, yes mostly.
> For v2, someone would have to add a invalid LAR pseudoheader to the
> final linked image. 
No invalid header needed. No pseudo header anyways. Just pack a plain
normal valid header there.

> Definitely not something I'd like to try (my linker
> script skills are not good enough nor do I consider this to be a
> particularly compelling idea).
Placing a few bytes at an arbitrary 16byte aligned address within the
image is quite simple.

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