indir.2

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th INDIR II 8/5/73
.sh NAME
indir \*- indirect system call
.sh SYNOPSIS
(indir = 0.; not in assembler)
.br
.ft B
sys indir; syscall
.ft R
.sh DESCRIPTION
The system call at the location
.it syscall
is executed.
Execution resumes after the
.it indir
call.
.s3
The main purpose of
.it indir
is to allow a program to
store arguments in system calls and execute them
out of line in the data segment.
This preserves the purity of the text segment.
.s3
If
.it indir
is executed indirectly,
it is a no-op.
If the instruction at the indirect
location is not a system call,
the executing process will get a fault.
.sh "SEE ALSO"
\*-
.sh DIAGNOSTICS
\*-