Merge pull request #1987 from tlaurion/bugfix-reboot_using_syscall

initrd/bin/reboot bugfix: switch from sysrq instant reset to busybox' s reboot kernel syscall (so tpm2.0 does not increment TPM DA counter by one)

Author: tlaurion

config/busybox.config

@@ -500,7 +500,7 @@ CONFIG_FEATURE_XARGS_SUPPORT_ARGS_FILE=y
 # CONFIG_FEATURE_BOOTCHARTD_CONFIG_FILE is not set
 # CONFIG_HALT is not set
 # CONFIG_POWEROFF is not set
-# CONFIG_REBOOT is not set
+CONFIG_REBOOT=y
 # CONFIG_FEATURE_WAIT_FOR_INIT is not set
 # CONFIG_FEATURE_CALL_TELINIT is not set
 CONFIG_TELINIT_PATH=""

initrd/bin/reboot

@@ -3,15 +3,6 @@
 
 TRACE_FUNC
 
-if [ "$CONFIG_DEBUG_OUTPUT" = "y" ]; then 
-	#Generalize user prompt to continue reboot or go to recovery shell 
-	read -r -n 1 -s -p "Press any key to continue reboot or 'r' to go to recovery shell: " REPLY 
-	echo 
-	if [ "$REPLY" = "r" ] || [ "$REPLY" = "R" ]; then 
-		recovery "Reboot call bypassed to go into recovery shell to debug"
-	fi 
-fi
-
 # Shut down TPM
 if [ "$CONFIG_TPM" = "y" ]; then
 	tpmr shutdown
@@ -23,5 +14,26 @@ echo s > /proc/sysrq-trigger
 # Remount all mounted filesystems in read-only mode
 echo u > /proc/sysrq-trigger
 
-# Immediately reboot the system, without unmounting or syncing filesystems
-echo b > /proc/sysrq-trigger
+if [ "$CONFIG_DEBUG_OUTPUT" = "y" ]; then
+	#Generalize user prompt to continue reboot or go to recovery shell 
+	read -r -n 1 -s -p "Press any key to continue reboot or 'r' to go to recovery shell: " REPLY 
+	echo 
+	if [ "$REPLY" = "r" ] || [ "$REPLY" = "R" ]; then 
+		recovery "Reboot call bypassed to go into recovery shell to debug"
+	fi 
+fi
+
+if [ "$CONFIG_DEBUG_OUTPUT" = "y" ]; then
+	DEBUG "DEBUG: TPM shutdown and filesystem operations complete"
+	read -r -p "Press Enter to issue final reboot syscall: "
+fi
+
+# Use busybox reboot explicitly (symlinks removed to avoid conflicts)
+if busybox --help 2>&1 | grep -q reboot; then
+	DEBUG "Using busybox reboot syscall for orderly shutdown"
+	busybox reboot -f
+else
+	# Fallback to sysrq if busybox doesn't have reboot support
+	DEBUG "Busybox reboot not available, falling back to sysrq"
+	echo b > /proc/sysrq-trigger
+fi

modules/busybox

@@ -32,6 +32,11 @@ $(initrd_bin_dir)/busybox: $(build)/$(busybox_dir)/.build
 		| tee -a $(build)/log/busybox.log \
 		$(VERBOSE_REDIRECT) \
 	)
+	# Remove busybox's reboot symlink that conflicts with our custom script
+	$(call do,RM-SYMLINKS,bin/busybox,\
+		rm -f $(initrd_bin_dir)/../sbin/reboot \
+		$(VERBOSE_REDIRECT) \
+	)
 	@touch $< # ensure that our build file is still newer