On 21/02/14 02:02, Justin Roylance wrote:
Ok, so I have downloaded and compiled flashrom from source and it sees
my Winbond flash chip "W25Q64.V". When I first installed coreboot I
backed up my original firmware, but I have two files. The first is from
the command "flashrom -r stock-firmware.rom", and the second is from the
command "chromeos-firmwareupdate --sb_extract ." Both files are the
same size, but diff tells me that they are different. I understand that
the first one is the stock firmware read straight from the flash chip,
and the second command gets you a copy of the parts of the current
firmware which can't be read by flashrom if running on the target
machine. So, which one of these two files do I flash back into my C7?
They should be identical save for a missing/invalid serial number from
the (S)hell(Ball) created ROM. Flash back the backup ROM.
I read at http://chromebooklinux.blogspot.com/2013_09_01_archive.html
that you can check the validity of a firmware backup by looking at
address 0x00001000 of the firmware file, if that byte contains 0xFF the
backup is invalid, but neither of my two original backup files have 0xFF
at that address.
Basically, if you backed the ROM up when the write-protect screw/jumper
was still on, you would have a Management Engine binary which is
garbage. Even that is okay though, as it won't completely brick your
Chromebook, it will just switch it off every 30 mins.
Since I haven't completely bricked my chromebook I
want to make sure I don't flash a bad firmware backup in as this might
be my last chance to save it without requiring an external programmer.
I'm still not sure what went wrong with the original flash, it sounds as
though the PCI id's in the ROM for the graphics card are wrong, except
that normally you'd get a completely blank screen, not a blue one. I'll
have to keep an eye out if anyone else reports that issue.
John.
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