1. Motivation

• 1983
• over 500 system calls × multiple errors = 8 bits of errno ?!? ; slide
• disconnect:
  • the user has no idea
  • the kernel knows
• The car is up on the hoist, and we are locking at the underside.
  Mud, crud, and ugly (functional, but ugly).

1.1 Error Messages as Finesse

• each is < 1% of project effort
• user benefit exceeds effort
• what the errors look like to the user
  • segfault; slide
  • can't open file; slide
  • perror("open"); slide
  • perror(filename); slide
  • "open %s: %s", filename, strerror; slide

1.2 Limitations of perror and strerror

• describes the error number; slide
• the kernel knows; slide
• the file name problem; slide
• 1980s, PDP11, no resources

1.3 Level Infinity Support

• Never ever talk to users; slide
• Test team need translations; slide
• Level 1 help desk need translations
• Enough! ; slide