kbuild: fix delay in setlocalversion on readonly source

Do not update index on read only media.
Idea published by Christian Kujau <lists@nerdbynature.de>.

Cc: Nico Schottelius <nico@ikn.schottelius.org>
Cc: Christian Kujau <lists@nerdbynature.de>

1 files changed, 4 insertions, 2 deletions

diff --git a/scripts/setlocalversion b/scripts/setlocalversion
index 00790472f641..46989b88d734 100755
--- a/scripts/setlocalversion
+++ b/scripts/setlocalversion
@@ -39,8 +39,10 @@ if head=`git rev-parse --verify --short HEAD 2>/dev/null`; then
                 printf -- '-svn%s' "`git svn find-rev $head`"
         fi
 
-        # Are there uncommitted changes?
-        git update-index --refresh --unmerged > /dev/null
+        # Update index only on r/w media
+        [ -w . ] && git update-index --refresh --unmerged > /dev/null
+
+        # Check for uncommitted changes
         if git diff-index --name-only HEAD | grep -v "^scripts/package" \
             | read dummy; then
                 printf '%s' -dirty