v5.9.3

skiboot-5.9.3

skiboot 5.9.3 was released on Wednesday November 22nd, 2017. It replaces
skiboot-5.9.2 as the current stable release in the 5.9.x series.

Over skiboot-5.9.2, we have one NPU2/NVLink2 fix that causes the machine
to crash hard in the event of hardware error rather than crash
mysteriously later on whenever the NVLink2 links are used.

That fix is:

• npu2: hw-procedures: Add check_credits procedure

  As an immediate mitigator for a current hardware glitch, add a
  procedure that can be used to validate NTL credit values. This will
  be called as a safeguard to check that link training succeeded.

  Assert that things are exactly as we expect, because if they aren't,
  the system will experience a catastrophic failure shortly after the
  start of link traffic.