1UCALL(2)                      System Calls Manual                     UCALL(2)
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NAME

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

9       #include <pdp/psl.h>
10       #include <sys/types.h>
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12       ucall(priority, function, arg0, arg1)
13       int priority, arg0, arg1;
14       caddr_t function;
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DESCRIPTION

17       Ucall causes the processor priority to be set to priority and the spec‐
18       ified kernel function to be called with arguments arg0 and arg1.   Pri‐
19       ority  is one of PSL_BR0, ..., PSL_BR7.  Processor priority is reset to
20       PSL_BR0 when function returns.
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22       Ucall is allowed only if the user is the superuser.   It  is  obviously
23       extremely  dangerous  if  misused.   It's only current use is at system
24       boot time to configure system devices by calling device drivers ...
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ERRORS

27       [EPERM]        The caller is not the super-user.
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SEE ALSO

30       autoconfig(8)
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BUGS

33       No address validations are attempted.
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35       Ucall is unique to the PDP-11 and 2BSD; its use is discouraged.
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393rd Berkeley Distribution      January 22, 1987                       UCALL(2)