When CPU errors, service processor damage, storage errors, or channel
subsystem errors occur, except for some I/O errors, the hardware notifies
the operating system with a machine check interruption. Machine check
interruptions fall into one of three classes depending on the severity
of the error. The classes are:
- Soft (or repressible) errors: Least severe
type. Generally these errors do not affect the operation of the task
currently in control. Soft errors can be disabled (repressed) so that
they do not cause a machine check interruption.
- Hard errors: Malfunctions that affect the
processing of the current instruction or make incorrect the contents
of hardware areas, such as registers.
- Terminating error
- s: Malfunctions that affect the operation of a CPU.
Hard and terminating errors are also referred to as exigent errors.