Make LoadKernel() pass back the kernel partition's UniqueGuid.

Make LoadKernel() pass back the kernel partition's UniqueGuid.

LoadKernel already returns the partition number for the selected kernel.
This change makes it also return the GPT Entry's UniqueGuid, which will
eventually be passed to the kernel itself, so the kernel can determine which
of several possible devices it has booted from. It doesn't know for certain
because the BIOS and the kernel may enumerate the devices in a different
order.

BUG=chromium-os:4984

[vb, 2010-07-23 01:26:26]

On Thu, Jul 22, 2010 at 6:21 PM, <wfrichar@chromium.org> wrote:
>
> Reviewers: Randall Spangler, vb, gauravsh,
>
> Description:
> Make LoadKernel() pass back the kernel partition's UniqueGuid.
>
> LoadKernel already returns the partition number for the selected kernel.
> This change makes it also return the GPT Entry's UniqueGuid, which will
> eventually be passed to the kernel itself, so the kernel can determine which
> of several possible devices it has booted from. It doesn't know for certain
> because the BIOS and the kernel may enumerate the devices in a different
> order.
>

How did you test this? the procedure should be included in the CL description,

cheers,
/vb

> BUG=4984
>
> Please review this at http://codereview.chromium.org/3056014/show
>
> SVN Base: ssh://git@chromiumos-git//vboot_reference.git
>
> Affected files:
>  M firmware/include/load_kernel_fw.h
>  M firmware/lib/cgptlib/cgptlib_internal.c
>  M firmware/lib/cgptlib/include/cgptlib_internal.h
>  M firmware/lib/vboot_kernel.c
>  M firmware/version.c
>  M utility/load_kernel_test.c
>
>

[Bill Richardson, 2010-07-23 01:47:26]

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).

[gauravsh, 2010-07-23 01:50:57]

lgtm provided you have already tested this and update the issue description as
per Vadim's comment

http://codereview.chromium.org/3056014/diff/1/5
File firmware/lib/vboot_kernel.c (right):

http://codereview.chromium.org/3056014/diff/1/5#newcode17
firmware/lib/vboot_kernel.c:17: #include "cgptlib_internal.h"
nit: alpha order