I386_GET_LDT(2) (i386)

I386_GET_LDT(2) | System Calls Manual (i386) | I386_GET_LDT(2)

# NAME

`i386_get_ldt`, `i386_set_ldt` —
manage i386 per-process Local Descriptor Table entries

# LIBRARY

i386 Architecture Library (libi386, -li386)

# 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);

# DESCRIPTION

`i386_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 and are defined in `<i386/segments.h> .` These structures are defined by the architecture as disjoint bit-fields, so care must be taken in constructing them.

# RETURN VALUES

Upon successful completion, `i386_get_ldt`() returns the number of descriptors 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.

# ERRORS

`i386_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

i386 Microprocessor Programmer's Reference Manual, Intel

# WARNING

You can really hose your process using this.

September 20, 1993 | NetBSD 9.0