@@ -17,10 +17,6 @@ if [ ! -d "$D" ]; then
echo >&2 "$D does not exist: Malformed kernel source tree?"
exit 1
fi
-if [ -s "$D/initrd/init" ]; then
- echo "$D/initrd/init already exists, no need to create it"
- exit 0
-fi
# Create a C-language initrd/init infinite-loop program and statically
# link it. This results in a very small initrd.
@@ -29,8 +25,10 @@ cd $D
mkdir -p initrd
cd initrd
-# Generate the init.c with optional command
-cat > init.c << 'EOF_HEAD'
+# Generate an init-tmp.c with optional command. This will then be compared
+# with any existing init.c. The reason for this is, we want to force a
+# rebuild if the optional command or command line arguments have changed.
+cat > init-tmp.c << 'EOF_HEAD'
#ifndef NOLIBC
#include <unistd.h>
#include <sys/time.h>
@@ -45,7 +43,7 @@ if [ $# -gt 0 ]; then
# If command provided, generate run_optional_command() with the specified command.
# We use printf to generate the command and args.
# Example: echo $(printf '"%s", ' cmd a1 a2) gives: "cmd", "a1", "a2",
- cat >> init.c << EOF
+ cat >> init-tmp.c << EOF
pid_t pid = fork();
if (pid == 0) {
char *args[] = {$(printf '"%s", ' "$@")NULL};
@@ -54,11 +52,11 @@ if [ $# -gt 0 ]; then
EOF
else
# If no command provided, function will be empty
- echo " /* No command specified */" >> init.c
+ echo " /* No command specified */" >> init-tmp.c
fi
# Add the rest of the program
-cat >> init.c << 'EOF_TAIL'
+cat >> init-tmp.c << 'EOF_TAIL'
}
int main(int argc, char *argv[])
@@ -95,6 +93,23 @@ int main(int argc, char *argv[])
}
EOF_TAIL
+# Check if init.c exists and compare with init-tmp.c
+if [ -f "init.c" ]; then
+ if ! cmp -s "init.c" "init-tmp.c"; then
+ mv "init-tmp.c" "init.c"
+ else
+ rm "init-tmp.c"
+ fi
+else
+ mv "init-tmp.c" "init.c"
+fi
+
+# Now check if init binary exists and is up to date
+if [ -s "init" ] && [ "init" -nt "init.c" ]; then
+ echo "$D/initrd/init already exists and is up to date"
+ exit 0
+fi
+
# build using nolibc on supported archs (smaller executable) and fall
# back to regular glibc on other ones.
if echo -e "#if __x86_64__||__i386__||__i486__||__i586__||__i686__" \
@@ -120,7 +135,6 @@ then
exit "$ret"
fi
-rm init.c
echo "Done creating a statically linked C-language initrd"
exit 0
Create the init.c as a temporary init-tmp.c file, even if init already exists. Ensure the existing init.c matches this. If init.c doesn't exist in initrd/ then skip the check and assume init-tmp.c as the new init.c. After that, check if init binary already exists as we did before and skip the build if it does. This does mean we keep a copy of init.c around in the initrd but this is a small file and it is useful to see for debugging anyway. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> --- .../selftests/rcutorture/bin/mkinitrd.sh | 34 +++++++++++++------ 1 file changed, 24 insertions(+), 10 deletions(-)