I386_GET_LDT(2) BSD Programmer's Manual (i386) I386_GET_LDT(2)NAME
i386_get_ldt, i386_set_ldt - manage i386 per-process Local Descriptor
Table entries
SYNOPSIS
#include <sys/types.h>
#include <machine/segments.h>
#include <machine/sysarch.h>
int
i386_get_ldt(int start_sel, union descriptor *descs, int num_sels);
int
i386_set_ldt(int start_sel, union descriptor *descs, int num_sels);
DESCRIPTIONi386_get_ldt() will return the list of i386 descriptors that the process
has in its LDT. i386_set_ldt() will set a list of i386 descriptors for
the current process in its LDT. Both routines accept a starting selector
number start_sel, an array of memory that will contain the descriptors to
be set or returned descs, and the number of entries to set or return
num_sels.
The argument descs can be either segment_descriptor or gate_descriptor,
as defined in <i386/segments.h>. These structures are defined by the ar-
chitecture as disjoint bit-fields, so care must be taken in constructing
them.
Before this API can be used the functionality has to be enabled using the
machdep.userldt sysctl(8) variable.
Note: Code using the i386_get_ldt() and i386_set_ldt() functions must be
compiled using -li386.
RETURN VALUES
Upon successful completion, i386_get_ldt() returns the number of descrip-
tors currently in the LDT. i386_set_ldt() returns the first selector set.
Otherwise, a value of -1 is returned and the global variable errno is set
to indicate the error.
ERRORSi386_get_ldt() and i386_set_ldt() will fail if:
[EINVAL] An inappropriate parameter was used for start_sel or num_sels.
[EACCES] The caller attempted to use a descriptor that would circumvent
protection or cause a failure.
REFERENCES
Intel, i386 Microprocessor Programmer's Reference Manual.
WARNING
You can really hose your process using this.
MirOS BSD #10-current September 20, 1993 1
