[coreboot] C720 swapparoo

Gregg Levine gregg.drwho8 at gmail.com
Thu Jan 30 01:11:12 CET 2014

Oddly enough Aaron the first one knew who my Google Mail address was,
but did not know what page it was. Whereas your second one worked.

Now the important one which is, what does this do? And do we need to worry?
Gregg C Levine gregg.drwho8 at gmail.com
"This signature fought the Time Wars, time and again."

On Wed, Jan 29, 2014 at 5:25 PM, Aaron Durbin <adurbin at google.com> wrote:
> On Wed, Jan 29, 2014 at 4:16 PM, John Lewis <jlewis at johnlewis.ie> wrote:
>> 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.
> Try cherry-picking this one:
> https://chrome-internal-review.googlesource.com/153037
> -Aaron
> --
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