UCALL(2)            UNIX Programmer's Manual             UCALL(2)

NAME
     ucall - call a kernel subroutine from user mode

SYNOPSIS
     #include <sys/psw.h>
     #include <sys/types.h>

     ucall(priority, function, arg0, arg1)
     int priority, arg0, arg1;
     caddr_t function;

DESCRIPTION
     _U_c_a_l_l causes the processor priority to be set to _p_r_i_o_r_i_t_y
     and the specified _f_u_n_c_t_i_o_n to be called with arguments _a_r_g_0
     and _a_r_g_1.  _P_r_i_o_r_i_t_y is one of PS_BR0, ..., PS_BR7.  Proces-
     sor priority is reset to PS_BR0 when _f_u_n_c_t_i_o_n returns.

     _U_c_a_l_l is allowed only if the user is the superuser.  It is
     obviously extremely dangerous if misused.

ERRORS
     _U_c_a_l_l will fail if:

     [EPERM]             The process's effective user ID is not
                         the super-user.

SEE ALSO
     autoconfig(8)

BUGS
     No address validations are attempted.

ASSEMBLER
     (local = 58., ucall = 9.)
     sys local; 9f
     . . .
     .data
     9: sys ucall; priority; function; arg0; arg1

Printed 7/30/83                                                 1