update_kernel: Get kernel commandline arguments w/ vbutil

Using the vbutil program 'dump_kernel_config' will give us the
pre-mangled commandline arguments. This helps in cases where we're
updating a vboot kernel and want to use the unmodified commandline
parameters such as 'PARTUUID=%U'. It also helps avoid
https://crbug.com/907772 that had to cut down on the number of
cros_secure that /proc/cmdline had because depthcharge adds it even when
it's already present.

TEST=Update kernel on cheza using remote bootargs, see same commandline
arguments as before

Change-Id: I97f0870252b1abc63104da02b963cf91cb6046a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/1933595
Tested-by: Stephen Boyd <swboyd@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed