util/smmstoretool: support processing ROMs

Input file is parsed for FMAP and SMMSTORE region which is used if
found.  Otherwise, the whole file is assumed to be the region.  Passing
an image with FMAP that lacks SMMSTORER is an error.

Change-Id: Ieab555d7bbcfa4dadf6a5070d1297acd737440fb
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80903
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

1 files changed, 18 insertions, 6 deletions

diff --git a/Documentation/util/smmstoretool/index.md b/Documentation/util/smmstoretool/index.md
index f7af60579d..5be6ffc79b 100644
--- a/Documentation/util/smmstoretool/index.md
+++ b/Documentation/util/smmstoretool/index.md
@@ -4,13 +4,20 @@ Offline SMMSTORE variable modification tool.
 
 ## Operation
 
+### File formats
+
+To discover SMMSTORE, the tool first looks for FMAP header and, if found, for
+SMMSTORE region.  If FMAP is found but it has no SMMSTORE region, that's an
+error.  If there is no FMAP, the whole file is assumed to be SMMSTORE
+region (e.g., extracted via `cbfstool`).
+
 ### Storage initialization
 
 If SMMSTORE presence isn't detected and an update operation is requested, the
-store spanning the whole file is created automatically.  Size of the store file
-must be a multiple of 64 KiB (block size in version 2 of SMMSTORE protocol),
-the variable storage itself will be 64 KiB in size.  That's the way EDK2 makes
-use of it.
+store spanning the whole region is created automatically.  Size of the store
+region must be a multiple of 64 KiB (block size in version 2 of SMMSTORE
+protocol), the variable storage itself will be 64 KiB in size.  That's the way
+EDK2 makes use of it.
 
 Unlike online editing which mostly appends new variable entries each storage
 update with this tool drops all deleted or incomplete entries.
@@ -28,7 +35,7 @@ Start with:
 
 ```
 $ smmstoretool -h
-Usage: smmstoretool smm-store-file sub-command
+Usage: smmstoretool smm-store-file|rom sub-command
        smmstoretool -h|--help
 
 Sub-commands:
@@ -58,7 +65,8 @@ to typical configuration values are supported:
 
 ## Examples
 
-`SMMSTORE` is the name of a file containing SMMSTORE data.
+`SMMSTORE` is the name of a file containing SMMSTORE data or a full ROM image
+with FMAP that includes SMMSTORE region.
 
 ### Variable listing
 
@@ -111,9 +119,13 @@ $ smmstoretool SMMSTORE remove -g dasharo -n NetworkBoot
 If one edits a newly generated Dasharo `coreboot.rom`:
 
 ```bash
+# editing exported storage
 cbfstool coreboot.rom read -r SMMSTORE -f SMMSTORE
 smmstoretool SMMSTORE set -g dasharo -n NetworkBoot -t bool -v true
 cbfstool coreboot.rom write -r SMMSTORE -f SMMSTORE
+
+# editing in-place storage
+smmstoretool coreboot.rom set -g dasharo -n NetworkBoot -t bool -v true
 ```
 
 On the first boot, "Network Boot" setting will already be enabled.