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 -- coreboot mailing list: [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
