tools: Add a README note about fw_printenv lock file

Add a mention of the lock file to the README for the fw_printenv tool.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Reported-by: Luka Perkov <uboot@lukaperkov.net>

diff --git a/tools/env/README b/tools/env/README
index 3f0d77e2aad76527e9b630f818a61cede0138cbf..df020e4afd43d4540937a834ea8be14c9e0ed466 100644 (file)
--- a/tools/env/README
+++ b/tools/env/README
@@ -55,3 +55,7 @@ partition where the environment resides.
 DEVICEx_ENVSECTORS defines the number of sectors that may be used for
 this environment instance. On NAND this is used to limit the range
 within which bad blocks are skipped, on NOR it is not used.
+
+To prevent losing changes to the environment and to prevent confusing the MTD
+drivers, a lock file at /var/lock/fw_printenv.lock is used to serialize access
+to the environment.