Re: [coreboot] C720 swapparoo

[John Lewis]

On 29/01/14 22:03, Aaron Durbin wrote:
 
 This is where we reach the crux of the matter - In the stock/shellball
 firmware, extracting BOOT_STUB doesn't yield a file which cbfstool in
 upstream coreboot or CrOS coreboot can decipher. Looking at the file in
 hexedit it appears to be almost identical to a CBFS that is recognised, but
 that's it. I have managed to extract the SVGA binary from the CBFS in the
 RW_LEGACY slot, and I've made an educated guess as to where the system-agent
 begins and ends in the unrecognised CBFS (section beginning "LARCHIVE
 mrc.bin" or similar with the binary itself following, surrounded by FF's)
 copying and pasting it to a file. I would like to know if I am correct in my
 assumptions about extracting that file manually and what size it should be,
 in bytes?
 That's interesting. It is just a regular 'ol cbfs. The images that
 shipped with your device is an 8MiB SPI. First 2MiB Duncan covered.
 The next 5 have nothing to do w/ coreboot proper -- all the extra
 vboot firmware bits. The last 1MiB is the cbfs.
Okay, well I extracted the attached file using:

eval `./fmap_decode bios.bin | grep BOOT_STUB`
dd if=c720.rom ibs=$((area_offset)) skip=1 | dd bs=$((area_size)) 
iflag=fullblock of=c720-coreboot.bin

and:

../coreboot/build/cbfstool c720-coreboot.bin print

produces:

c720-coreboot.bin:
1024 kB, bootblocksize 3144, romsize 8388608, offset 0x700000
alignment: 64 bytes

Name                           Offset     Type         Size

zippo.