Basic hard-coded alarm system

[troglobit]

Errors encountered at startup, or validating system, should trigger alarms. For example:

• Broken VPD
• Missing secondary bootloader
• Broken primary bootloader
• Broken Linux partition
• Broken startup-config
• Broken failure-config

When encountered at boot (or during background checksumming after boot) these errors could simply be written to a structure in /run/system/alarm/, and if this (and subdirectories) are non-empty we trigger a summary alarm that in turn can trigger a LED indication.

/run/
  `- system/
      `- alarm/
          |- hw/
          |   `- broken-vpd.log
          |- bootloader/
          |   `- broken-primary.log
          |- infix/
          `- misc/

The contents are logged, at the time of detection, and also saved here for later replication and debugging.