Dell 5580: fix original or clean foreign?

Special Topics Intel Management Engine
1

Hello!

I have Dell 5580 with no boot. Apparently BIOS region is corrupted upon update and likely not ME issue.

dell_5580
dell_5580965Ă—680 48.4 KB

  1. Is there a kind of guide to follow in order to determine what is wrong in dump (some common evidences?) and either go with ME clean or BIOS region recovery procedure?

  2. Another question.
    I found a dump from the very same motherboard and it boots w/o any modifications, everything seems to work fine. The problem with this BIOS is a long (30 seconds) boot. Gotcha! This is the exact reason for ME cleaning.
    The clean ME dump boots super fast, but damn - LAN issue.
    What could cause LAN issue after ME clean? Did I miss/replaced ME settings?

Attached are:

  1. original corrupted BIOS, service tag: 8K77BH2
  2. working dirty BIOS from other machine with long boot
  3. working clean BIOS from other machine with fast boot, but LAN issue
    dell_5580
2

Always use as many parts of your own dump as possible.

For example: When cleaning an ME make sure you take the config from your own dump and compare it to the foreign dump. The foreign ME you used and cleaned had a slightly different config than yours, might work, might not- see L460. Migh take some time afterwards.

66660
666601875Ă—300 270 KB

.
Compare the images and the parser messages:

66661
666611433Ă—915 329 KB

Here the volume can’t get decompressed, that’s a brick.
.

Check for the machine specific info- Dell often uses a DVAR region, try to find your service tag, serial (often encrypted or stored in TPM now)
(Search - tab text - try with unicode on and off)

66662
666621290Ă—1028 366 KB

So third volume is machine specific parts, first two is NVRAM, all in bios region from including fourth volume seems static, might be replaced with stock bios parts…
BUT there might be version conflicts to EC firmware or ME or… so best to stay on same version or version close to original version.

Finding the original firmware version isn’t too easy, Dell hasn’t too many hints hidden. You might limit the range by microcode versions and ME versions. For this bios it’s 1.4.3

Compare bricked firmware and original bios region in HxD, go to the end and start upward:

66663
666631374Ă—798 331 KB

There you have it: It’s a bit flip, not seen very often, but possible! Region / address is correct for the error already found, if you go further you’ll find both images identical up to the DVAR region, that’s good enough!

So change 0x91E898 from 54 to 50 and you’re possibly good to go again! Or try the attached file, only change made as written.
original_rec.zip (8.2 MB)

(An error during bios update would normally result in a whole block not written/ erased and parts of bios region new version, parts still old)

I don’t have an explanation for the LAN issue after cleaning, can you explain the issue more detailed?

3

So, in this particular case not a block was written or not written, but a single byte! - how is that possible during BIOS update run?

The fixed BIOS works like a charm - fast boot and no LAN issue! Single byte and machine is alive again!

This is a second time in a row I get LAN issue, when try to clean ME myself, and it looks like this in device manager.

LAN_issue
LAN_issue1024Ă—303 43.1 KB

4

Thanks for the feedback :+1:

Well, NVRAM gets constantly rewritten, parts of the ME might change, so these firmware chips aren’t completely static any longer.

But this bit flip is just an unstable bit, this didn’t happen during an update!
0x54 = 0101 0100
0x50 = 0101 0000

Proof is that before and after all is 100% identical to the same bios version! Might be a symptom for a dying SPI chip or might never happen again…

I don’t have any valid explanation for the LAN issue.

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