On 7/17/19 12:31 PM, Ahmad Fatoum wrote: > > > On 17/7/19 12:02, Roland Hieber wrote: >> On Tue, Jul 16, 2019 at 12:58:36PM +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. >> >> I would also add this paragraph to the kconfig help text, so it is more >> visible for users. > > Maybe add a priority parameter like we do with e.g. reset reason? > That way we can have a base machine-id in the OTP, but board code can > override it with e.g. an EEPROM value which is given higher priority. Hm, that makes things complicated. At the end everybody will have their own high priority call like.. machine_id_set_hashable(my_board_specific_info, len, 99); .. to have a machine id that persists such an update scenario? That does not sound too good to me.. Any opinions on this? Bastian -- Pengutronix e.K. Industrial Linux Solutions http://www.pengutronix.de/ Peiner Str. 6-8, 31137 Hildesheim, Germany Amtsgericht Hildesheim, HRA 2686 _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
