[coreboot] .cb files

Peter Stuge peter at stuge.se
Tue Jan 4 12:16:45 CET 2011

ali hagigat wrote:
> So devicetree.cb files are written by hand and the compilation
> process does not use them? They are just some information for the
> developers?

Of course not, that would be redundant. As Kerry pointed out, they
are very much part of the build process. You can also see this very
clearly when watching the make output.

> #device pci 1e.2 off end # AC'97 Audio
> It means that AC'97 Audio is on Bus#=1 and Function#=2?

I don't know about the bus number because you took the above line out
of context, but device 0x1e function 2 yes.

> But all the devices of the south bridge, ICH7 are on Bus number 0,
> as far as I know.
> Why you have not written, Bus number, Function number, Device number,
> Register number clearly.

Because it is not a list of registers. Device and function is there
and bus is implicit, but the file encodes more complex knowledge
about the board than simply a list of register/value pairs.

> device pci 1d.0 on end, What does it mean, 1d.0?

Device 0x1d function 0. I would hope that this is obvious with a
little knowledge about the respective chipset. If you have the lspci
next to you I think that devicetree.cb is rather clear.

The bus number is implicit because the file is structured rather than
a simple list. The indentation and the "end" keywords try to make
this obvious.

Again, please say how you think the information can be structured in
a better way.


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