MirOS Manual: syscall(2), __syscall(2)

SYSCALL(2)                 BSD Programmer's Manual                  SYSCALL(2)


     syscall, __syscall - indirect system call


     #include <sys/syscall.h>
     #include <unistd.h>

     syscall(int number, ...);

     __syscall(quad_t number, ...);


     syscall() performs the system call whose assembly language interface has
     the specified number with the specified arguments. Symbolic constants for
     system calls can be found in the header file <sys/syscall.h>.

     Since different system calls have different return types, a prototype of
     __syscall specifying the correct return type should be declared locally.
     This is especially important for system calls returning larger-than-int

     The __syscall form should be used when one or more of the parameters is a
     64-bit argument to ensure that argument alignment is correct. This system
     call is useful for testing new system calls that do not have entries in
     the C library.


     The return values are defined by the system call being invoked. In gen-
     eral, for system calls returning int, a 0 return value indicates success.
     A -1 return value indicates an error, and an error code is stored in


     The syscall() function call appeared in 4.0BSD.


     There is no way to simulate system calls that have multiple return values
     such as pipe(2).

MirOS BSD #10-current           June 16, 1993                                1

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