1MODIFY_LDT(2)              Linux Programmer's Manual             MODIFY_LDT(2)
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NAME

6       modify_ldt - get or set ldt
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SYNOPSIS

9       #include <sys/types.h>
10       #include <linux/unistd.h>
11       #include <errno.h>
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13       _syscall3(int, modify_ldt, int, func, void *, ptr,
14                 unsigned long, bytecount)
15                 /* Using syscall(2) may be preferable; see intro(2) */
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17       int modify_ldt(int func, void *ptr, unsigned long bytecount);
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DESCRIPTION

20       modify_ldt()  reads  or  writes  the local descriptor table (ldt) for a
21       process.  The ldt is a per-process memory management table used by  the
22       i386  processor.   For more information on this table, see an Intel 386
23       processor handbook.
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25       When func is 0, modify_ldt() reads the ldt into the memory  pointed  to
26       by  ptr.   The number of bytes read is the smaller of bytecount and the
27       actual size of the ldt.
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29       When func is 1, modify_ldt() modifies one ldt entry.  ptr points  to  a
30       modify_ldt_ldt_s  structure  and  bytecount must equal the size of this
31       structure.
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RETURN VALUE

34       On success, modify_ldt() returns either the actual number of bytes read
35       (for  reading) or 0 (for writing).  On failure, modify_ldt() returns -1
36       and sets errno.
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ERRORS

39       EFAULT ptr points outside the address space.
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41       EINVAL ptr is 0, or func is 1 and bytecount is not equal to the size of
42              the  structure  modify_ldt_ldt_s,  or  func is 1 and the new ldt
43              entry has invalid values.
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45       ENOSYS func is neither 0 nor 1.
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CONFORMING TO

48       This call is Linux specific and should not be used in programs intended
49       to be portable.
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SEE ALSO

52       vm86(2)
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56Linux 1.3.6                       1995-07-22                     MODIFY_LDT(2)