[coreboot] Intel SCH CMC(Chipset Microcode) state machine binary?

Alp Eren Köse alperenkose at buyutech.com.tr
Mon Oct 24 13:11:33 CEST 2011

Thanks a lot for the information.
physrd is also a very nice and useful utility, it works on my board..

2011/10/21 Peter Stuge <peter at stuge.se>

> Alp Eren Köse wrote:
> > > > But unfortunately I needed a windoz machine to extract the CMC
> binary,
> > > > you can use the CBROM utility like this:
> > > > C:\> CBROM32_195.EXE vendor_bios.bin /TOPHOLE:FFFD0000 extract
> > > I'd say you can do the same with dd(1), no?
> > >
> > Oh yes of course, that's very likely probably :) that should be something
> > like this maybe:
> > dd skip=(blocks until FFFD0000) if=vendor_bios.bin of=cmc.bin
> > is that right? I'm not good at those block calculations:)
> The theory is in the right direction but the details are wrong, and
> the command can't work at all.
> () creates a subshell in most if not all shells; not what you want.
> To give dd the correct parameters you need to know where cmc.bin
> starts. FFFD0000 is not the answer; it is the correct physical
> address when the factory BIOS image is in a flash chip that the CPU
> can address, but it is obviously not the correct offset in the file.
> You know that the factory BIOS image is mapped to top of 4GB physical
> address, so you need to use subtraction to find the correct offset:
> offset = 0xfffd0000 - (0x100000000 - size of factory BIOS image)
> Then you need to express the offset in a way that dd understands. As
> you know from the dd man page, dd uses blocks, and you can set any
> block size you want. Since a factory BIOS image size will always be a
> multiple of 64KB, and this is how much you want to copy, and since
> all other terms in the above equation are 64KB aligned, and since it
> is such a nice round number in binary and hexadecimal, 64KB seems
> like a good block size. Translate the offset into number of blocks:
> offset_in_blocks = offset / 65536
> And run dd:
> dd if=factor_bios.bin of=cmc.bin bs=64k skip=offset_in_blocks count=1
> Another method is to use http://stuge.se/physrd.c to try to read from
> the flash chip directly, then you do not need to do maths, but on the
> other hand you must compile a special program and if you are unlucky
> the address region is not accessible by the CPU without special magic
> that flashom knows. You would run:
> ./physrd 0xfffd0000 64k cmc.bin
> I think the calculation is faster and simpler.
> //Peter
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