futility: updater: Preserve all sections with FMAP_AREA_PRESERVE set

Many projects started their initial builds without knowing that some
sections must be preserved when being updated. This may be solved by
adding section name to 'preserved' list in firmware updater (for
instance, CL:1239797), or include that section as sub area of
{RO,RW}_PRESERVE.

However, there are problems in both solutions. For example, installing
an older image will run old updater, which will not preserve the new
names.  Also, if there are multiple sections must be preserved (and not
contiguous - see CL:1493629) there will be problems.  Additionally,
changing FMAP layout usually causes more problems.

As a result, adding the description in FMAP area would be the better
idea. A new FMAP_AREA_PRESERVE suggests firmware updater to preserve
a section if possible. In Coreboot, this can be easily set in *.fmd
using flag (PRESERVE). See https://review.coreboot.org/31709 for
example.

BUG=chromium:936768
TEST=make futil; tests/futility/run_test_scripts.sh $(pwd)/build/futility
BRANCH=None

Change-Id: Ie56f65dd418faa97ffb78b1acff613e7d7e268b8
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1495054
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/host/lib/include/fmap.h b/host/lib/include/fmap.h
index d6c33c65..02f97c2d 100644
--- a/host/lib/include/fmap.h
+++ b/host/lib/include/fmap.h
@@ -27,6 +27,14 @@ typedef struct _FmapHeader {
 	uint16_t    fmap_nareas;
 } __attribute__((packed)) FmapHeader;
 
+enum fmap_flags {
+	FMAP_AREA_STATIC	= 1 << 0,
+	FMAP_AREA_COMPRESSED	= 1 << 1,
+	FMAP_AREA_RO		= 1 << 2,
+	/* Should be preserved on update or rollback. */
+	FMAP_AREA_PRESERVE	= 1 << 3,
+};
+
 typedef struct _FmapAreaHeader {
 	uint32_t area_offset;
 	uint32_t area_size;