[Buildroot] [PATCH 6/7 v3] package/petitboot: Add petitboot, the userspace bootloader

[Arnout Vandecappelle <arnout@mind.be>]

 Hi Jeremy,

On 17/06/14 07:21, Jeremy Kerr wrote:
> This change adds the petitboot package, a bootloader that exists in
> userspace, and uses the kexec facility to boot into a new kernel.
> 
> We add a little extra infrastructure to get things integrated into a
> buildroot environment:
> 
>  - scripts to make kexec work with busybox init, for a clean shutdown
> 
>  - udev rules to get removable event notifications, and start the
>    petitboot UI processes
> 
>  - startup scripts for the device-discovery process
> 
> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
> 
> ---
>  package/Config.in                            |    1 
>  package/petitboot/Config.in                  |   21 +++++++
>  package/petitboot/S14silence-console         |    9 +++
>  package/petitboot/S15pb-discover             |   23 +++++++
>  package/petitboot/kexec-restart              |    8 ++
>  package/petitboot/petitboot-console-ui.rules |    5 +
>  package/petitboot/petitboot.mk               |   57 +++++++++++++++++++
>  package/petitboot/removable-event-poll.rules |    4 +
>  8 files changed, 128 insertions(+)
> 
> diff --git a/package/Config.in b/package/Config.in
> index b0d4d47..a769d33 100644
> --- a/package/Config.in
> +++ b/package/Config.in
> @@ -1116,6 +1116,7 @@ endif
>  	source "package/ncdu/Config.in"
>  	source "package/numactl/Config.in"
>  	source "package/nut/Config.in"
> +	source "package/petitboot/Config.in"
>  	source "package/powerpc-utils/Config.in"
>  	source "package/polkit/Config.in"
>  if BR2_PACKAGE_BUSYBOX_SHOW_OTHERS
> diff --git a/package/petitboot/Config.in b/package/petitboot/Config.in
> new file mode 100644
> index 0000000..d1e1783
> --- /dev/null
> +++ b/package/petitboot/Config.in
> @@ -0,0 +1,21 @@
> +config BR2_PACKAGE_PETITBOOT
> +	bool "petitboot"
> +	# petitboot needs udev /dev management
> +	depends on BR2_PACKAGE_HAS_UDEV

 It looks to me that it also relies on udhcpc, which would mean you need to
depend on BUSYBOX. But of course, the thing still works even without udhcpc, it
would just not react to dhcp/bootp, right?


> +	select BR2_PACKAGE_NCURSES
> +	select BR2_PACKAGE_NCURSES_TARGET_PANEL
> +	select BR2_PACKAGE_NCURSES_TARGET_FORM
> +	select BR2_PACKAGE_NCURSES_TARGET_MENU
> +	# run-time dependency only
> +	select BR2_PACKAGE_KEXEC_LITE if !BR2_PACKAGE_KEXEC
> +	# run-time dependency only
> +	select BR2_PACKAGE_POWERPC_UTILS if BR2_powerpc || BR2_powerpc64
> +	# run-time dependency only
> +	select BR2_PACKAGE_IPRUTILS if BR2_powerpc || BR2_powerpc64
> +	help
> +	  Petitboot is a small kexec-based bootloader

 We probably want a little more explanation about how you can use petitboot,
i.e. make a very small buildroot config with just petitboot and an initramfs
filesystem, and use that to boot a full-fledged system which doesn't even need
to be buildroot-based.

> +
> +	  http://www.kernel.org/pub/linux/kernel/people/geoff/petitboot/petitboot.html
> +
> +comment "petitboot requires udev to be enabled"
> +	depends on !BR2_PACKAGE_HAS_UDEV
> diff --git a/package/petitboot/S14silence-console b/package/petitboot/S14silence-console
> new file mode 100755
> index 0000000..6570200
> --- /dev/null
> +++ b/package/petitboot/S14silence-console
> @@ -0,0 +1,9 @@
> +#!/bin/sh
> +
> +case "$1" in
> +    start)
> +        echo 0 0 7 0 > /proc/sys/kernel/printk
> +        ;;
> +esac

 Why is this needed? I mean, we could do this in general in buildroot but do we
really want it?

> +
> +exit 0
> diff --git a/package/petitboot/S15pb-discover b/package/petitboot/S15pb-discover
> new file mode 100755
> index 0000000..ebdf944
> --- /dev/null
> +++ b/package/petitboot/S15pb-discover
> @@ -0,0 +1,23 @@
> +#!/bin/sh
> +
> +LOGFILE=/var/log/petitboot/pb-discover.log
> +PIDFILE=/var/run/petitboot.pid
> +
> +case "$1" in
> +    start)
> +        ulimit -c unlimited
> +        mkdir -p $(dirname $LOGFILE)
> +        PATH=/usr/bin:/usr/sbin:/bin:/sbin pb-discover -l $LOGFILE &
> +        echo $! > $PIDFILE
> +        ;;
> +    stop)
> +        pid=$(cat $PIDFILE)
> +        [ -n "$pid" ] && kill -TERM $pid

 Why are we not using start-stop-daemon here like in all other init scripts?

> +        ;;
> +    *)
> +        echo "Usage: $0 {start|stop}"
> +        exit 1
> +        ;;
> +esac
> +
> +exit 0
> diff --git a/package/petitboot/kexec-restart b/package/petitboot/kexec-restart
> new file mode 100755
> index 0000000..0175e76
> --- /dev/null
> +++ b/package/petitboot/kexec-restart
> @@ -0,0 +1,8 @@
> +#!/bin/sh
> +
> +/usr/sbin/kexec -f -e
> +
> +while :
> +do
> +    sleep 1
> +done

 Can you shed some light about why this script is needed and why it's not part
of petitboot itself?

> diff --git a/package/petitboot/petitboot-console-ui.rules b/package/petitboot/petitboot-console-ui.rules
> new file mode 100644
> index 0000000..7464856
> --- /dev/null
> +++ b/package/petitboot/petitboot-console-ui.rules
> @@ -0,0 +1,5 @@
> +
> +# spawn a petitboot UI on common user-visible interface devices
> +SUBSYSTEM=="tty", KERNEL=="hvc*", RUN+="/usr/libexec/petitboot/pb-console --getty --detach -- -n -i 0 $name vt100"
> +SUBSYSTEM=="tty", KERNEL=="tty0", RUN+="/usr/libexec/petitboot/pb-console --getty --detach -- -n -i 0 $name vt100"
> +SUBSYSTEM=="tty", KERNEL=="ttyS*", RUN+="/usr/libexec/petitboot/pb-console --getty --detach -- -n -i 0 $name vt100"

 It would make a lot more sense to me to use BR2_TARGET_GENERIC_GETTY_PORT and
leave it up to the user to update the ui-rules for his particular configuration,
if necessary.

> diff --git a/package/petitboot/petitboot.mk b/package/petitboot/petitboot.mk
> new file mode 100644
> index 0000000..1bbf522
> --- /dev/null
> +++ b/package/petitboot/petitboot.mk
> @@ -0,0 +1,57 @@
> +################################################################################
> +#
> +# petitboot
> +#
> +################################################################################
> +
> +PETITBOOT_VERSION = 509fca5ca2733a741521ae4332400d54d95ee073
> +PETITBOOT_SITE = git://ozlabs.org/~jk/petitboot
> +PETITBOOT_DEPENDENCIES = ncurses udev host-bison host-flex
> +PETITBOOT_LICENSE = GPLv2
> +PETITBOOT_LICENSE_FILES = COPYING
> +
> +PETITBOOT_AUTORECONF = YES
> +PETITBOOT_AUTORECONF_OPT = -i
> +PETITBOOT_CONF_OPT += --with-ncurses --without-twin-x11 --without-twin-fbdev \
> +	      --localstatedir=/var \
> +	      HOST_PROG_KEXEC=/usr/sbin/kexec \
> +	      HOST_PROG_SHUTDOWN=/usr/libexec/petitboot/bb-kexec-reboot \
> +	      $(if $(BR2_PACKAGE_BUSYBOX),--with-tftp=busybox)

 Indentation should be just a single tab.

 With so many options, I prefer one per line. But that's just nitpicking.

> +
> +ifdef PETITBOOT_DEBUG
> +PETITBOOT_CONF_OPT += --enable-debug
> +endif

 I guess these three lines should be removed?

> +
> +ifeq ($(BR2_PACKAGE_NCURSES_WCHAR),y)
> +PETITBOOT_CONF_OPT += --with-ncursesw MENU_LIB=-lmenuw FORM_LIB=-lformw
> +endif
> +
> +PETITBOOT_PRE_CONFIGURE_HOOKS += PETITBOOT_PRE_CONFIGURE_BOOTSTRAP

 PETITBOOT_PRE_CONFIGURE_BOOTSTRAP doesn't seem to be defined.

> +
> +define PETITBOOT_POST_INSTALL

 Instead of _POST_INSTALL, we generally use more specific names like
PETITBOOT_INSTALL_CONFIG_AND_SCRIPTS. But again, that's just nitpicking.

> +	$(INSTALL) -D -m 0755 $(@D)/utils/bb-kexec-reboot \
> +		$(TARGET_DIR)/usr/libexec/petitboot
> +	$(INSTALL) -d -m 0755 $(TARGET_DIR)/etc/petitboot/boot.d
> +	$(INSTALL) -D -m 0755 $(@D)/utils/hooks/01-create-default-dtb \
> +		$(TARGET_DIR)/etc/petitboot/boot.d/
> +	$(INSTALL) -D -m 0755 $(@D)/utils/hooks/20-set-stdout \
> +		$(TARGET_DIR)/etc/petitboot/boot.d/
> +
> +	$(INSTALL) -D -m 0755 package/petitboot/S14silence-console \
> +		$(TARGET_DIR)/etc/init.d/
> +	$(INSTALL) -D -m 0755 package/petitboot/S15pb-discover \
> +		$(TARGET_DIR)/etc/init.d/

 These should be installed using the PETITBOOT_INSTALL_INIT_SYSV commands. Not
that it's very likely that someone will use petitboot+systemd, but who knows...

> +	$(INSTALL) -D -m 0755 package/petitboot/kexec-restart \
> +		$(TARGET_DIR)/usr/sbin/
> +	$(INSTALL) -D -m 0755 package/petitboot/petitboot-console-ui.rules \
> +		$(TARGET_DIR)/etc/udev/rules.d/
> +	$(INSTALL) -D -m 0755 package/petitboot/removable-event-poll.rules \
> +		$(TARGET_DIR)/etc/udev/rules.d/
> +
> +	ln -sf /usr/sbin/pb-udhcpc \
> +		$(TARGET_DIR)/usr/share/udhcpc/default.script.d/

 Even though after patch 1/7 this directory is created in busybox, you should
still create the directory here as well. Especially because you don't depend on
busybox so it may not have been created yet.

> +endef
> +
> +PETITBOOT_POST_INSTALL_TARGET_HOOKS += PETITBOOT_POST_INSTALL
> +
> +$(eval $(autotools-package))
> diff --git a/package/petitboot/removable-event-poll.rules b/package/petitboot/removable-event-poll.rules
> new file mode 100644
> index 0000000..b736aef
> --- /dev/null
> +++ b/package/petitboot/removable-event-poll.rules
> @@ -0,0 +1,4 @@
> +
> +# petitboot needs notification for media change events on removable devices,
> +# which we only get if we've set the poll_msecs sysfs attribute.
> +ACTION!="remove", ATTR{removable}=="1", ATTR{events_poll_msecs}="2000"

 Why is this not part of petitboot itself?


 Regards,
 Arnout

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-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
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