On Fri, Jul 19, 2019 at 12:55:33PM +0200, Bastian Krause wrote: > By default systemd generates a machine id on first boot and tries to > persist it (see `man machine-id`). When the root file system is read-only > systemd cannot persist the machine id. In case multiple redundant slots > are used the machine id will vary. When not handled explicitly the > machine id will also change during updates. > > It is possible to pass a machine id to the kernel which will be used by > systemd (systemd.machine_id=). > > This adds functionality to pass device-specific information that will be > hashed to generate a persistent unique machine id. The machine id will > be finally added to the kernel parameters via the > linux.bootargs.machine_id global variable. > > Note: if multiple sources provide hashable device-specific information > (via machine_id_set_hashable()) the information provided by the last call > prior to the late initcall set_machine_id() is used to generate the > machine id from. Thus when updating barebox the machine id might change. > > Signed-off-by: Bastian Krause <bst@xxxxxxxxxxxxxx> > --- > Changes since (implicit) v1: > - depend on SHA1 instead of selecting DIGEST/DIGEST_SHA1_GENERIC > - add note about multiple sources providing hashables to kconfig > - add note about no hashable provided to kconfig > - remove warning about "no hashable info provided" along with pr_fmt > - make machine_id_set_hashable()'s hashable parameter const > - make a copy of the hashable provided rather than storing the pointer > - hash data instead of pointer address > - use basprintf() and dedicated variables for hex machine id/machine id > bootarg > - add static inline wrapper if CONFIG_MACHINE_ID is disabled > --- > common/Kconfig | 18 +++++++++++++ > common/Makefile | 1 + > common/machine_id.c | 63 ++++++++++++++++++++++++++++++++++++++++++++ > include/machine_id.h | 16 +++++++++++ > 4 files changed, 98 insertions(+) > create mode 100644 common/machine_id.c > create mode 100644 include/machine_id.h > > diff --git a/common/Kconfig b/common/Kconfig > index 8aad5baecd..7be2487a20 100644 > --- a/common/Kconfig > +++ b/common/Kconfig > @@ -982,6 +982,24 @@ config RESET_SOURCE > of the reset and why the bootloader is currently running. It can be > useful for any kind of system recovery or repair. > > +config MACHINE_ID > + bool "pass machine-id to kernel" > + depends on FLEXIBLE_BOOTARGS > + depends on SHA1 > + help > + Sets the linux.bootargs.machine_id global variable with a value of > + systemd.machine_id=UID. The UID is a persistent device-specific > + id. It is a hash over device-specific information provided by various > + sources. > + > + Note: if multiple sources provide hashable device-specific information > + (via machine_id_set_hashable()) the information provided by the last call > + prior to the late initcall set_machine_id() is used to generate the > + machine id from. Thus when updating barebox the machine id might change. > + > + Note: if no hashable information is available no machine id will be passed > + to the kernel. We'll need some additional runtime control knob whether this behaviour should be used or not. Just enabling a Kconfig option shouldn't change the behaviour of barebox. A boolean global.linux.provide_machine_id flag should do it. Also it would be nice to provide the machine-id to barebox aswell, maybe in global.machine_id. Overall we then get this: - set global.machine_id during barebox startup (inicalls) - User can overwrite it with nv.machine_id if necessary - during booting of Linux global.linux.bootargs.machine_id is initialized with the value of global.machine_id if desired (based on global.linux.provide_machine_id) Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
