Create a new command update_kernel.sh

Create a new command update_kernel.sh

This command can be used to update the kernel of a ChromiumOS target.

Much thanks to snanda for the inspiration and instructions.

BUG=9864
TEST=Verified that it works.

Change-Id: I66f7d940e0dc59b0e1a50409a7155fe0ba7157fe

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=a63cd2d

[Olof Johansson, 2010-12-02 04:43:03]

I've always envisioned having a tool ran locally on the target instead (so it'd
be gmerge + local tool to install), but this should work equally well.

Only thing I think is missing that /lib/modules and /lib/firmware isn't copied
over, which could cause problems. Care to add an rsync (with --delete) for
those?

[Sameer Nanda, 2010-12-02 17:22:41]

LGTM modulo olofj's comment regarding /lib/modules & /lib/firmware not getting
copied over.

http://codereview.chromium.org/5550001/diff/3001/update_kernel.sh
File update_kernel.sh (right):

http://codereview.chromium.org/5550001/diff/3001/update_kernel.sh#newcode26
update_kernel.sh:26: remote_sh cat /proc/cmdline
probably simpler to use "rootdev" instead.

[Mandeep Singh Baines, 2010-12-02 17:24:36]

olofj@chromium.org (olofj@chromium.org) wrote:
> I've always envisioned having a tool ran locally on the target
> instead (so it'd
> be gmerge + local tool to install), but this should work equally well.
> 
> Only thing I think is missing that /lib/modules and /lib/firmware
> isn't copied
> over, which could cause problems. Care to add an rsync (with --delete) for
> those?
> 

I avoided that in this first cut because of the complexity involved and I
didn't need it for my own needs.

Cool if I add that later or let someone else add it?

You'd need to handle re-mounting the rootfs rw and then update the hash.
Updating the hash is the hard part. I guess for the non-verity case,
you could avoid all that.

I could add an explicit warning for now.

> 
> http://codereview.chromium.org/5550001/

[Olof Johansson, 2010-12-02 19:23:38]

This is way better than nothing. Launch and iterate :)

LGTM.