From: Reza Arbab <arbab@linux.ibm.com>
To: buildroot@buildroot.org
Date: Wed, 15 Nov 2023 15:59:29 -0600
Message-Id: <20231115215931.860940-4-arbab@linux.ibm.com>
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Subject: [Buildroot] [PATCH v4 3/5] package/petitboot: fix shutdown
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Cc: Laurent Vivier <laurent@vivier.eu>, Joel Stanley <joel@jms.id.au>
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It's good practice to unmount filesystems and gracefully terminate
running services before running "kexec -e". So when a boot option has
been chosen from the petitboot menu, poke init to shut the system down
and kexec the new kernel.

One benefit to us in particular is that when pb-console is killed, it
notifies the user that we're booting:

  trap 'reset; echo "SIGTERM received, booting..."; sleep 2' SIGTERM

This terminal reset is also useful, exiting the ncurses visual mode so
subsequent boot output is raw rather than being confined to the window
set up for the petitboot menu.

Currently we assume busybox init, but do not add an accompanying entry
in the inittab to run kexec, so things aren't working. Fix this and
accomodate the other buildroot init systems as well.

Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
---
 package/petitboot/kexec-restart | 26 ++++++++++++++++++++++++++
 package/petitboot/petitboot.mk  | 20 +++++++++++++++++---
 2 files changed, 43 insertions(+), 3 deletions(-)
 create mode 100644 package/petitboot/kexec-restart

diff --git a/package/petitboot/kexec-restart b/package/petitboot/kexec-restart
new file mode 100644
index 000000000000..14e6899f70bb
--- /dev/null
+++ b/package/petitboot/kexec-restart
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+case "$(/usr/bin/readlink -f /proc/1/exe)" in
+	/bin/busybox)
+		# inittab "restart" runlevel entry runs kexec
+		/bin/kill -QUIT 1
+		;;
+	/sbin/init)
+		# inittab runlevel 6 entry runs kexec
+		/sbin/shutdown -r now
+		;;
+	/sbin/openrc-init)
+		/sbin/openrc-shutdown --kexec now
+		;;
+	/usr/lib/systemd/systemd)
+		/usr/bin/systemctl kexec
+		;;
+	*)
+		/usr/sbin/kexec -f -e
+		;;
+esac
+
+while :
+do
+	sleep 1
+done
diff --git a/package/petitboot/petitboot.mk b/package/petitboot/petitboot.mk
index 28e29c02ea26..fc1c5da03742 100644
--- a/package/petitboot/petitboot.mk
+++ b/package/petitboot/petitboot.mk
@@ -21,7 +21,7 @@ PETITBOOT_CONF_OPTS = \
 	--without-twin-x11 \
 	$(if $(BR2_PACKAGE_BUSYBOX),--enable-busybox,--disable-busybox) \
 	HOST_PROG_KEXEC=/usr/sbin/kexec \
-	HOST_PROG_SHUTDOWN=/usr/libexec/petitboot/bb-kexec-reboot
+	HOST_PROG_SHUTDOWN=/usr/sbin/kexec-restart
 
 # HPA and Busybox tftp are supported. HPA tftp is part of Buildroot's tftpd
 # package.
@@ -46,17 +46,31 @@ else
 PETITBOOT_CONF_OPTS += --without-fdt
 endif
 
+ifeq ($(BR2_INIT_BUSYBOX),y)
+define PETITBOOT_BUSYBOX_INITTAB
+	grep -q kexec $(TARGET_DIR)/etc/inittab || \
+		printf "\nnull::restart:/usr/sbin/kexec -f -e\n" >> $(TARGET_DIR)/etc/inittab
+endef
+PETITBOOT_TARGET_FINALIZE_HOOKS += PETITBOOT_BUSYBOX_INITTAB
+else ifeq ($(BR2_INIT_SYSV),y)
+define PETITBOOT_SYSV_INITTAB
+	grep -q kexec $(TARGET_DIR)/etc/inittab || \
+		$(SED) 's~^reb0:.*~reb0:6:wait:/usr/sbin/kexec -f -e~' $(TARGET_DIR)/etc/inittab
+endef
+PETITBOOT_TARGET_FINALIZE_HOOKS += PETITBOOT_SYSV_INITTAB
+endif
+
 PETITBOOT_GETTY_PORT = $(patsubst %,'%',$(call qstrip,$(BR2_PACKAGE_PETITBOOT_GETTY_PORT)))
 
 define PETITBOOT_POST_INSTALL
-	$(INSTALL) -D -m 0755 $(@D)/utils/bb-kexec-reboot \
-		$(TARGET_DIR)/usr/libexec/petitboot/bb-kexec-reboot
 	$(INSTALL) -D -m 0755 $(@D)/utils/hooks/01-create-default-dtb \
 		$(TARGET_DIR)/etc/petitboot/boot.d/01-create-default-dtb
 	$(INSTALL) -D -m 0755 $(@D)/utils/hooks/90-sort-dtb \
 		$(TARGET_DIR)/etc/petitboot/boot.d/90-sort-dtb
 	$(INSTALL) -D -m 0755 $(PETITBOOT_PKGDIR)/S15pb-discover \
 		$(TARGET_DIR)/etc/init.d/S15pb-discover
+	$(INSTALL) -D -m 0755 $(PETITBOOT_PKGDIR)/kexec-restart \
+		$(TARGET_DIR)/usr/sbin/kexec-restart
 	$(INSTALL) -D -m 0755 $(PETITBOOT_PKGDIR)/pb-console \
 		$(TARGET_DIR)/etc/init.d/pb-console
 
-- 
2.39.3

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