[coreboot] Lenovo N20p Chromebook
Aaron Durbin
adurbin at google.com
Fri Sep 19 20:11:15 CEST 2014
On Fri, Sep 19, 2014 at 12:20 PM, John Lewis <jlewis at johnlewis.ie> wrote:
>
>
> On 19/09/14 18:07, Aaron Durbin wrote:
>>
>> On Fri, Sep 19, 2014 at 12:01 PM, John Lewis <jlewis at johnlewis.ie> wrote:
>>>
>>>
>>>
>>> On 16/09/14 02:05, Aaron Durbin wrote:
>>>>
>>>>
>>>> On Mon, Sep 15, 2014 at 3:46 PM, John Lewis <jlewis at johnlewis.ie> wrote:
>>>>>
>>>>>
>>>>> On 15/09/14 23:17, Aaron Durbin wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Sep 15, 2014 at 5:13 PM, John Lewis <jlewis at johnlewis.ie>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 15/09/14 23:10, Aaron Durbin wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mon, Sep 15, 2014 at 5:00 PM, John Lewis <jlewis at johnlewis.ie>
>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 15/09/14 22:50, Aaron Durbin wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Mon, Sep 15, 2014 at 4:29 PM, John Lewis <jlewis at johnlewis.ie>
>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 15/09/14 22:03, Aaron Durbin wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Mon, Sep 15, 2014 at 3:35 PM, John Lewis
>>>>>>>>>>>> <jlewis at johnlewis.ie>
>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Hello,
>>>>>>>>>>>>>
>>>>>>>>>>>>> I've purchased the subject Chromebook with a view to getting
>>>>>>>>>>>>> some
>>>>>>>>>>>>> sort
>>>>>>>>>>>>> of
>>>>>>>>>>>>> custom ROM going for Baytrail based Chromebooks, and I have my
>>>>>>>>>>>>> first
>>>>>>>>>>>>> brick
>>>>>>>>>>>>> of the day.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I'm using ChromeOS coreboot and the firmware-clapper-5218.B
>>>>>>>>>>>>> branch.
>>>>>>>>>>>>> As
>>>>>>>>>>>>> per
>>>>>>>>>>>>> the advice Aaron gave me regarding the ASUS C200 some time ago,
>>>>>>>>>>>>> I
>>>>>>>>>>>>> extracted
>>>>>>>>>>>>> the reference code binary and changed line 111 in
>>>>>>>>>>>>> src/arch/x86/Makefile.inc
>>>>>>>>>>>>> as follows:
>>>>>>>>>>>>>
>>>>>>>>>>>>> $(CBFSTOOL) $@.tmp add -f
>>>>>>>>>>>>> $(CONFIG_REFCODE_BLOB_FILE)
>>>>>>>>>>>>> -n
>>>>>>>>>>>>> $(CONFIG_CBFS_PREFIX)/refcode -t raw
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> I think I might know. You are using upstream, right? This is my
>>>>>>>>>>>> fault.
>>>>>>>>>>>> The rmodule format changed. We didn't bump the version, and
>>>>>>>>>>>> dropped
>>>>>>>>>>>> the old code. Can you run readelf -e on that blob you extracted?
>>>>>>>>>>>> I
>>>>>>>>>>>> think I allowed ELF packaging for that file. If that doesn't
>>>>>>>>>>>> work
>>>>>>>>>>>> (hexdump -C) would be helpful.
>>>>>>>>>>>>
>>>>>>>>>>> No, I'm using ChromiumOS coreboot. With readelf -e I get:
>>>>>>>>>>>
>>>>>>>>>>> readelf -e refcode.bin
>>>>>>>>>>> readelf: Error: Unable to read in 0x7115 bytes of section headers
>>>>>>>>>>> readelf: Error: Not an ELF file - it has the wrong magic bytes at
>>>>>>>>>>> the
>>>>>>>>>>> start
>>>>>>>>>>>
>>>>>>>>>>> hexdump -C:
>>>>>>>>>>>
>>>>>>>>>>> hexdump -C refcode.bin
>>>>>>>>>>> 00000000 01 00 00 00 00 10 00 00 00 00 00 00 00 00 00 00
>>>>>>>>>>> |................|
>>>>>>>>>>> 00000010 00 00 00 00 ac 10 00 00 b8 4b 00 00 01 00 60 00
>>>>>>>>>>> |.........K....`.|
>>>>>>>>>>> 00000020 00 a0 4b 00 00 00 00 00 00 00 7f 3f ec 22 15 71
>>>>>>>>>>> |..K........?.".q|
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> snip
>>>>>>>>>>
>>>>>>>>>>> 000010b0 ea 88 85 74 8b 20 1e db 6b 09 b3 c0 40 c3 eb ed
>>>>>>>>>>> |...t.
>>>>>>>>>>> ..k... at ...|
>>>>>>>>>>> 000010c0 48 a8 8d c4 08 32 85 80
>>>>>>>>>>> |H....2..|
>>>>>>>>>>> 000010c8
>>>>>>>>>>>
>>>>>>>>>>> You may want to snip that. ;)
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> OK. A couple of things. Bear with me as I use this thread to think
>>>>>>>>>> things through. This file is compressed. We extracted it, and
>>>>>>>>>> added
>>>>>>>>>> it
>>>>>>>>>> back using 'raw'. That means cbfs_file->type != CBFS_TYPE_STAGE.
>>>>>>>>>> So
>>>>>>>>>> refcode loading would not work. Would it create a brick? I
>>>>>>>>>> wouldn't
>>>>>>>>>> think so, but I haven't tried.
>>>>>>>>>>
>>>>>>>>>> Offhand, do you have the option rom? Do we see any life out of the
>>>>>>>>>> display? I'm trying to think of ways to see how far we've gotten
>>>>>>>>>> without serial console. Is MRC in the same place as the released
>>>>>>>>>> firmware? Perhaps a cbfstool print might be instructive on your
>>>>>>>>>> resulting image.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Yes, I extracted all the necessary files from the shellball ROM for
>>>>>>>>> Clapper.
>>>>>>>>> No, no life from the display (no backlight even).
>>>>>>>>>
>>>>>>>>> coreboot.rom: 8192 kB, bootblocksize 1184, romsize 8388608, offset
>>>>>>>>> 0x400000
>>>>>>>>> alignment: 64 bytes, architecture: x86
>>>>>>>>>
>>>>>>>>> Name Offset Type Size
>>>>>>>>> cmos_layout.bin 0x400000 cmos_layout 1164
>>>>>>>>> pci8086,0f31.rom 0x4004c0 optionrom 65536
>>>>>>>>> cpu_microcode_blob.bin 0x410500 microcode 103424
>>>>>>>>> config 0x429980 raw 4298
>>>>>>>>> fallback/refcode 0x42aa80 raw 4296
>>>>>>>>> (empty) 0x42bb80 null 17368
>>>>>>>>> fallback/romstage 0x42ff80 stage 35171
>>>>>>>>> fallback/coreboot_ram 0x438980 stage 71515
>>>>>>>>> fallback/payload 0x44a140 payload 34866
>>>>>>>>> img/Jeltka 0x4529c0 payload 2970296
>>>>>>>>> (empty) 0x727cc0 null 492248
>>>>>>>>> mrc.bin 0x79ffc0 (unknown) 70168
>>>>>>>>> (empty) 0x7b1240 null 240984
>>>>>>>>> spd.bin 0x7ebfc0 (unknown) 1536
>>>>>>>>> (empty) 0x7ec600 null 79064
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> After bricking the device can you re-flash the spi part back to a
>>>>>>>>>> released image?
>>>>>>>>>>
>>>>>>>>> I don't see why not, but it's getting late here and people are
>>>>>>>>> sleeping
>>>>>>>>> so
>>>>>>>>> I'll have to do that in the morning. If there's anything else quick
>>>>>>>>> I'll
>>>>>>>>> hang around this end for 10 or so minutes to answer.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Understood. The only thing I can think of trying really quickly is
>>>>>>>> making the type of the file to be a stage instead of raw. You'll
>>>>>>>> need
>>>>>>>> to hexedit the rom to change the type.
>>>>>>>>
>>>>>>>> -Aaron
>>>>>>>>
>>>>>>>
>>>>>>> Okay, fire away, I have it open and ready.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> In your rom, find the "LARCHIVE" tombstone with the appropriate name
>>>>>> afterwards ('fallback/refcode). It should be around offset 0x42aa80.
>>>>>> For reference:
>>>>>>
>>>>>> struct cbfs_file {
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> -------char magic[8];
>>>>>>> -------uint32_t len;
>>>>>>> -------uint32_t type;
>>>>>>> -------uint32_t checksum;
>>>>>>> -------uint32_t offset;
>>>>>>
>>>>>>
>>>>>>
>>>>>> } __attribute__((packed));
>>>>>>
>>>>>> We want to change the type field. There should be a hex 0x50
>>>>>> associated with the fallback/refcode file. Change that number to be
>>>>>> 0x10. Save and then cbfstool print should list the type as 'stage'.
>>>>>>
>>>
>>> I'm trying to flash the ROM externally now, but it's telling me it can't
>>> disable block protection. It gets as far as trying to erase 0x600000,
>>> then
>>> goes through all the erase functions, finally crapping out. Do you know
>>> how
>>> I can work-around that?
>>
>>
>> The write protect screw is removed, right? After that the flash's
>> write protect register needs to be updated. Do you know the status
>> register values? Flashrom should be able to do that.
>>
>
> Yes, it is definitely removed - I didn't put it back in after the initial
> brick. It says the register value is 0x94 - I did also hook up the Bus
> Pirate for use with statically linked ChromeOS Flashrom (as the particular
> version I have doesn't have Dediprog support) - I had an idea running
> --wp-disable might help, but it didn't recognise the chip and said the
> register was already 0x94 (paraphrasing). I am currently compiling a newer
> statically linked version of ChromeOS Flashrom using the SDK, in the hope
> that might be able to do the job. Am I barking up the wrong tree though, or
> is there something else I could do?
You are in the right spot. The fact that it failed at 6MiB is very
indicative of the SPI part write protection. There are, however, more
than one status register. There should be 3 of them:
Read Status Register-1 (05h), Status Register-2 (35h) & Status Register-3 (15h)
Btw, I'm referencing W25Q64FW datasheet.
-Aaron
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