1SYSTEMD-BOOT-SYSTEM-TOKEsNy.sStEeRmVdI-CbEo(o8t)-system-StYoSkTeEnM.Ds-eBrOvOiTc-eSYSTEM-TOKEN.SERVICE(8)
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6 systemd-boot-system-token.service - Generate an initial boot loader
7 system token and random seed
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10 systemd-boot-system-token.service
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13 systemd-boot-system-token.service is a system service that
14 automatically generates a 'system token' to store in an EFI variable in
15 the system's NVRAM and a random seed to store on the EFI System
16 Partition ESP on disk. The boot loader may then combine these two
17 randomized data fields by cryptographic hashing, and pass it to the OS
18 it boots as initialization seed for its entropy pool. The random seed
19 stored in the ESP is refreshed on each reboot ensuring that multiple
20 subsequent boots will boot with different seeds. The 'system token' is
21 generated randomly once, and then persistently stored in the system's
22 EFI variable storage.
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24 The systemd-boot-system-token.service unit invokes the bootctl
25 random-seed command, which updates the random seed in the ESP, and
26 initializes the 'system token' if it's not initialized yet. The service
27 is conditionalized so that it is run only when all of the below apply:
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29 · A boot loader is used that implements the Boot Loader Interface[1]
30 (which defines the 'system token' concept).
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32 · Either a 'system token' was not set yet, or the boot loader has not
33 passed the OS a random seed yet (and thus most likely has been
34 missing the random seed file in the ESP).
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36 · The system is not running in a VM environment. This case is
37 explicitly excluded since on VM environments the ESP backing
38 storage and EFI variable storage is typically not physically
39 separated and hence booting the same OS image in multiple instances
40 would replicate both, thus reusing the same random seed and 'system
41 token' among all instances, which defeats its purpose. Note that
42 it's still possible to use boot loader random seed provisioning in
43 this mode, but the automatic logic implemented by this service has
44 no effect then, and the user instead has to manually invoke the
45 bootctl random-seed acknowledging these restrictions.
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47 For further details see bootctl(1), regarding the command this service
48 invokes.
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51 systemd(1), bootctl(1), systemd-boot(7)
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54 1. Boot Loader Interface
55 https://systemd.io/BOOT_LOADER_INTERFACE
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59systemd 245 SYSTEMD-BOOT-SYSTEM-TOKEN.SERVICE(8)