MODIFY_LDT (2)

SYNOPSIS

#include <linux/ldt.h>
#include <linux/unistd.h>
_syscall3( int, modify_ldt, int, func, void *, ptr, unsigned long, bytecount )
  int modify_ldt(int  func , void * ptr , unsigned long  bytecount );  

DESCRIPTION

modify_ldt reads or writes the local descriptor table (ldt) for a process. 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.

RETURN VALUE

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 illegal values.

EFAULT

ptr points outside the address space.

CONFORMING TO

This call in Linux-specfic and should not be used in programs intended to be portable.

SEE ALSO

- vm86 (2) -