Notice

Before building, one is required to copy headers from /usr/src/include to /usr/include and from /usr/src/minix/include/minix to /usr/include/minix.

Changes made in this patch require remaking following directories (make && make install)

/usr/src/minix/kernel /usr/src/lib/libc /usr/src/minix/lib/libsys /usr/src/minix/commands/service /usr/src/minix/servers/pm /usr/src/minix/servers/sched

After making, one should make do-hdboot in /usr/src/releasetools and then reboot

System call order and specification:

• libc/misc/setsjf.c:
  • checks for argument errors
  • calls an available pm syscall and "pipes" eventual error codes
    • sets errno sign according to _SIGN (that seems to be opposite in this scope from how its value is defined in syscall scope
• pm/schedule.c::do_setsjf(void)
  • calls kernel call (which either fails or returns a new process priority
    • if it fails it returns an error code
  • if process has a scheduler, it calls a relevant sched call
  • returns 0 if OK or some errno.h status otherwise
• kernel/system/do_setsjf.c
  • checks if the process does or doesn't already belong to SJF
  • if the current state if correct, finds what the new priority for the state should be
  • remembers what was the last priority for this process to be able to revert when the process requests switching back to non-SJF
  • reschedules the process with a new priority and returns this new priority
  • a return status sign determines the type of output
    • _SIGN sign means an error
    • -(_SIGN) sign means a standard priority output
    • ...where (_SIGN) is a sign of errno.h errors as defined in default sys/errno.h header
• sched/schedule.c
  • updates its data about a given process