MODIFY_LDT(2) Linux Programmer's Manual MODIFY_LDT(2)
NAME
modify_ldt - get or set ldt
SYNOPSIS
#include<linux/ldt.h>
#include<linux/unistd.h>
_syscall3(int,modify_ldt,int, func,void*, ptr,unsignedlong, byte-
count)
intmodify_ldt(int func,void*ptr,unsignedlong bytecount);
DESCRIPTION
modify_ldt reads or writes the local descriptor table (ldt) for a pro-
cess. The ldt is a per-process memory management table used by the
i386 processor. For more information on this table, see an Intel 386
processor handbook.
When func is 0, modify_ldt reads the ldt into the memory pointed to by
ptr. The number of bytes read is the smaller of bytecount and the
actual size of the ldt.
When func is 1, modify_ldt modifies one ldt entry. ptr points to a
modify_ldt_ldt_s structure and bytecount must equal the size of this
structure.
RETURNVALUE
On success, modify_ldt returns either the actual number of bytes read
(for reading) or 0 (for writing). On failure, modify_ldt returns -1
and sets errno.
ERRORS
ENOSYS func is neither 0 nor 1.
EINVAL ptr is 0, or func is 1 and bytecount is not equal to the size of
the structure modify_ldt_ldt_s, or func is 1 and the new ldt
entry has invalid values.
EFAULT ptr points outside the address space.
CONFORMINGTO
This call in Linux-specific and should not be used in programs intended
to be portable.
SEEALSO
vm86(2)
Linux 1.3.6 1995-07-22 MODIFY_LDT(2)
Take our 
