---
name: "dwarf_set_frame_undefined_value"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/dwarf_set_frame_cfa_value"
---

# dwarf\_set\_frame\_undefined\_value(3)

set internal register rule table parameters

Part of [dwarf\_set\_frame\_cfa\_value(3)](/dwarf_set_frame_cfa_value/3.md).

## NAME

**dwarf\_set\_frame\_cfa\_value**, **dwarf\_set\_frame\_rule\_initial\_value**, **dwarf\_set\_frame\_rule\_table\_size**, **dwarf\_set\_frame\_same\_value**, **dwarf\_set\_frame\_undefined\_value** – set internal register rule table parameters

## LIBRARY

library “libdwarf”

## SYNOPSIS

**#include \<libdwarf.h\>**

*Dwarf\_Half*\

**dwarf\_set\_frame\_cfa\_value**(*Dwarf\_Debug dbg*, *Dwarf\_Half value*);

*Dwarf\_Half*\

**dwarf\_set\_frame\_rule\_initial\_value**(*Dwarf\_Debug dbg*, *Dwarf\_Half value*);

*Dwarf\_Half*\

**dwarf\_set\_frame\_rule\_table\_size**(*Dwarf\_Debug dbg*, *Dwarf\_Half value*);

*Dwarf\_Half*\

**dwarf\_set\_frame\_same\_value**(*Dwarf\_Debug dbg*, *Dwarf\_Half value*);

*Dwarf\_Half*\

**dwarf\_set\_frame\_undefined\_value**(*Dwarf\_Debug dbg*, *Dwarf\_Half value*);

## DESCRIPTION

These functions set the parameters of the internal register rule table.

Argument *dbg* should reference a DWARF debug context allocated using [dwarf\_init(3)](/dwarf_init/3.md).

Argument *value* should hold the parameter value to set.

Function **dwarf\_set\_frame\_cfa\_value**() sets the column number for the CFA register rule in the internal register rule table. The constant DW\_FRAME\_CFA\_COL is the default CFA register column number for DWARF2-only interfaces, and the constant DW\_FRAME\_CFA\_COL3 is the default CFA column number for DWARF3-compatible interfaces.

Function **dwarf\_set\_frame\_rule\_initial\_value**() sets the initial value of the register rules in the internal register rule table. The default initial value is the constant DW\_FRAME\_REG\_INITIAL\_VALUE, defined in the header file ⟨libdwarf.h⟩.

Function **dwarf\_set\_frame\_rule\_table\_size**() sets the maxmium number of columns of the internal register rule table. Argument *value* should be at least as large as the number of real registers in the ABI.

Function **dwarf\_set\_frame\_same\_value**() sets the register number representing the “same value” register rule. The default register number for the “same value” rule is the constant DW\_FRAME\_SAME\_VAL, defined in the header file ⟨libdwarf.h⟩.

Function **dwarf\_set\_frame\_undefined\_value**() sets the register number representing the “undefined” register rule. The default register number for the “undefined” rule is the constant DW\_FRAME\_UNDEFINED\_VAL, defined in the header file ⟨libdwarf.h⟩.

## RETURN VALUES

These functions return the previous value of the parameter being set.

## SEE ALSO

[dwarf(3)](/dwarf/3.md), [dwarf\_get\_fde\_at\_pc(3)](/dwarf_get_fde_at_pc/3.md), [dwarf\_get\_fde\_info\_for\_all\_regs(3)](/dwarf_get_fde_info_for_all_regs/3.md), [dwarf\_get\_fde\_info\_for\_all\_regs3(3)](/dwarf_get_fde_info_for_all_regs3/3.md), [dwarf\_get\_fde\_info\_for\_cfa\_reg3(3)](/dwarf_get_fde_info_for_cfa_reg3/3.md), [dwarf\_get\_fde\_info\_for\_reg(3)](/dwarf_get_fde_info_for_reg/3.md), [dwarf\_get\_fde\_info\_for\_reg3(3)](/dwarf_get_fde_info_for_reg3/3.md), [dwarf\_get\_fde\_n(3)](/dwarf_get_fde_n/3.md)