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4aaaeca130
This just adds the kernel_max_rollforward field to the nvstorage
libraries and crossystem. The firmware does not use it yet; that's
coming in a subsequent CL.
16 of the fields's 32 bits are taken from unused bytes of the kernel
field. This has no effect on existing usage.
BUG=chromium:783997
BRANCH=none
TEST=make runtests
Also manual testing. In a root shell:
crossystem kernel_max_rollforward --> Should default to 0
crossystem kernel_max_rollforward=0xfffffffe
crossystem kernel_max_rollforward --> Should be 0xfffffffe
(Note that setting it to 0xffffffff is indistinguishable from the
-1 value that the crossystem library uses to indicate error, so
0xffffffff isn't actually usable as a max rollforward limit. But
0xfffffffe is, and if we ever get so close to the limit that we
need to use 0xffffffff, something has already gone horribly wrong
with our versioning strategy...)
Change-Id: I008f412e6ed3c0b59beb9881268585af69d1ff2e
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/765572
Reviewed-by: Julius Werner <jwerner@chromium.org>
Here's what's what in the firmware/ directory. bdb/ Code for managing Boot Descriptor Blocks (BDB). include/ lib/ These are the original structures and APIs used in the earliest Chromebooks and continuing through 2014. It never had a version as such to begin with, but we now refer to this implementation as "vboot1" or "vboot version 1.0". linktest/ stub/ These are stubs used to link the vboot1 libraries into host-side test executables so we can run some tests on the build machine instead of a Chromebook. 2lib/ In 2014 we began work on a new vboot API. The first step was just a refactoring and renaming of the verification API. The public functions and external headers that are exported for use by the Chrome OS firmware (or anything else that wants to use vboot) live in here. The internal structures and implementations go elsewhere. lib20/ This is an early implementation of the public (2lib/) API. It is binary-compatible with vboot1, so although the interface details are different, any existing on-device structures or signatures created by the vboot1 tools can be validated using this implementation. This was deployed slightly before it was ready. That's not a problem, thanks to the binary compatibility, but this directory will be abandoned Real Soon Now, except for the product support branches. lib21/ This is where the current development of the second-generation vboot API is taking place. It uses the public (2lib/) API, but will NOT be binary compatible with vboot1 structs. Because of the early release of the lib20 stuff, we're actually calling this lib21.