MARK(2) Xinu Programmer's Manual MARK(2) NAME mark, unmarked - set and check initialization marks effi- ciently SYNOPSIS #include <mark.h> int mark(mk) MARKER mk; int unmarked(mk) MARKER mk; DESCRIPTION _M_a_r_k sets _m_k to "initialized", and records its location in the system. It returns 0 if the location is already marked, OK if the marking was successful, and SYSERR if there are too many marked locations. _U_n_m_a_r_k_e_d checks the contents and location of _m_k to see if it has been previously marked with the _m_a_r_k procedure. It returns OK if and only if _m_k has not been marked, 0 other- wise. The key is that they work correctly after a reboot, no matter what was left in the marked locations when the system stopped. Both _m_a_r_k and _u_n_m_a_r_k_e_d operate efficiently (in a few instructions) to correctly determine whether a location has been marked. They are most useful for creating self- initializing procedures when the system will be restarted. Both the value in _m_k as well as its location are used to tell if it has been marked. Memory marking can be eliminated from Xinu by removing the definition of the symbol MEMMARK from the Configuration file. Self-initializing library routines may require manual initialization if MEMMARK is disabled (e.g., see BUFFER(3)). BUGS Mark does not verify that the location given lies in the static data area before marking it; to avoid having the sys- tem retain marks for locations on the stack after procedure exit, do not mark automatic variables. Version 6b Printed 1/12/87 1