The failure message was

  NewBuildUpdateError: Failure in build R72-11168.0.0-rc1: System rolled back to previous build

which was caused by verify_boot_expectations() failed.

The DUT was updated with

  Updating image via: /usr/bin/update_engine_client --update --omaha_url=http://100.115.219.136:8082/update/link-paladin/R72-11168.0.0-rc1

The DUT got this inactive_kernel, or expected_kernel, before reboot. This was the desired kernel to reboot. Then the DUT was actually rebooted and the expected_kernel was compared against the active_kernel after the reboot. However, it was mysterious that they were not equal and thus the test failed. This required further investigation why the DUT did not reboot into the flashed expected_kernel.

Hi Prathmesh, could you take a look? Thanks!

The attributes of two kernel partitions looked suspicious

Before reboot, 
  "rootdev -s" showed  /dev/sda5
  "cgpt show -n -i 4 -P $(rootdev -s -d)" showed 1
  "cgpt show -n -i 2 -P $(rootdev -s -d)" showed 2
  Since 2 > 1, next reboot should boot into kernel A (partition 2)

However, after reboot,
  "rootdev -s" still showed  /dev/sda5
  "cgpt show" indicated that
     Label: "KERN-A"
       Attr: priority=0 tries=0 successful=0
     Label: "KERN-B"
       Attr: priority=1 tries=0 successful=1

So it still rebooted into Kernel B. Was it possible that the DUT tried to boot into Kernel A at its initial attempt but failed; and then it rebooted into Kernel B accordingly?



  

Hi Amin, you have submitted a CL about update payload. I am not sure if it is related with this failure. Could you help take a look to see if it is related? Thanks!

Hi Amin, I am sorry that I marked the CL (http://crrev.com/c/1234822) Verified -1 to test if it is related with this issue. I am very sorry if it is not.

Without the CL mentioned in C#4, link-paladin passed. Amin, the CL might be related. Please help take a look. Thanks!

Hi, Sorry, Yes, my CL was causing the issue. Unknown to me, major version 2 requires passing postinstall config to the delta generator. I'll have to address that separately so I'm closing this for now.