Export the kernel partition's UniqueGuid to the kernel command line.

Export the kernel partition's UniqueGuid to the kernel command line.

This will cause a %U in the kernel command line to be replaced with the
human-readable form of the kernel partition's UniqueGuid, which is passed
from the Chrome OS BIOS. If the BIOS doesn't pass this information (older
ones don't), %U expands to 00000000-0000-0000-0000-000000000000.

BUG=chromium-os:4941

[gauravsh, 2010-07-23 01:43:50]

lgtm

[Bill Richardson, 2010-07-23 01:47:34]

Testing:

This is a multiple-repository change set. All three of these
changes must have landed before any changes will be visible:

  http://codereview.chromium.org/3056014/show
  http://codereview.chromium.org/2832078/show
  http://codereview.chromium.org/3035020/show

AND a Chrome OS BIOS that incorporates CL 3056014 must also
be used.

If all that has happened, boot the device, log in, switch to
a console, and run

  cat /proc/cmdline

You should see a term something like this (the actual
numbers will be different):

  kern_guid=af208ed8-788f-6841-b250-8654755089a3


That GUID should correspond to the kernel partition, which
you can display using the cgpt tool. For example,

  sudo cgpt show /dev/sda

Of course, you'll want to replace /dev/sda with the actual
root device (which you can find by running "rootdev").


If the kern_guid numbers are all zeros or a simple '%U' or
is not present at all, not all changes have landed (or
something is broken).