2.11BSD/man/cat2/ucall.0

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



NAME
     ucall - call a kernel subroutine from user mode (2BSD)

SYNOPSIS
     #include <pdp/psl.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 kernel _f_u_n_c_t_i_o_n to be called with argu-
     ments _a_r_g_0 and _a_r_g_1.  _P_r_i_o_r_i_t_y is one of PSL_BR0, ...,
     PSL_BR7.  Processor priority is reset to PSL_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.	It's only current
     use is at system boot time to configure system devices by
     calling device drivers ...

ERRORS
     [EPERM]	    The caller is not the super-user.

SEE ALSO
     autoconfig(8)

BUGS
     No address validations are attempted.

     _U_c_a_l_l is unique to the PDP-11 and 2BSD; its use is
     discouraged.





















Printed 11/26/99	January 22, 1987			1