Analog Devices ee110 Application Notes

aa Engineer To Engineer Note EE-110

Technical Notes on using Analog Devices’ DSP components and development tools

Phone: (800) ANALOG-D, FAX: [phone], EMAIL: [e-mail], FTP: ftp.analog.com, WEB: www.analog.com/dsp

A Quick Primer on ELF and DWARF

Contributed by Ken Butler,
Assemblers and Simulator Products Manager

Introduction

The 4.1 VisualDSP® SHARC® and all newer
VisualDSP tools for other ADI DSPs will generate
ELF/DWARF-2 object files and executables. This
application note will help explain what this means
for users, especially users that have been using the

3.3 and 4.0 VisualDSP (SHARC) tools. It will also
explain why the change has been made.

ELF Object File Format

ELF (Executable and Linking Format) is an object
file format originally developed by Unix System
Laboratories. It was selected by the Tools
Interface Standards committee as the basis for a
portable object file format that works on a variety
of operating systems. Refer to the standard
“Executable and Linkable Format (ELF), Tools
Interface Standards (TIS), Portable Formats
Specification, Version 1.1.”

is a debugging information format that does not
favor the design of any compiler or debugger. It
was also designed to meet the debugging needs of
different languages in a unified manner. ADI uses
version 2 of the DWARF standard, sometimes
referred to as DWARF-2. Refer to the standard,
“DWARF Debugging Information Format, Tools
Interface Standards (TIS), Portable Formats
Specification, Version 1.1”.

In ADI tools, the debugging information produced
by the compiler and assembler is in DWARF-2
format. The VisualDSP debugger reads DWARF­2 debug information.

The software development tools for the ADSP­21160 (now in beta) and the ADSP-TS001 (now
in beta) are complete ELF/DWARF-2 toolsets.
The tools for the SHARC will be ELF/DWARF-2
starting with the 4.1 release. The ADSP-218x and
ADSP-219x tools will be ELF/DWARF-2 starting
with the 7.0 release. All toolsets for new processors
will be ELF/DWARF-2.

In the Analog Devices, Inc. (ADI) tools all linkable
objects (.doj) and all executable images (.dxe) are
stored as ELF files.

Previous formats

The 3.3 SHARC tools produced COFF object files
and executables. The debugging information was in
SDB. (A good reference for COFF and SDB is

ADI started using ELF in the 4.0 VisualDSP tools
for SHARC. Presently, the only ADI software
development tools that do not use ELF are the
ADSP-218x tools that generate AEXE; this will
change with the 7.0 release of the ADSP-218x
tools.

“Understanding and Using COFF” by Gintaras R.
Gircys”, O’reilly & Associates). The 4.0
VisualDSP SHARC tools used ELF object files but
maintained the SDB format for debug information.
The 4.1 SHARC tools will be an ELF/DWARF
toolset. (The table below shows object and debug
formats for ADI tools).

DWARF debug information format

DWARF is a format for the information generated
by compilers, assemblers and linkers that are
necessary for symbolic source-level debugging. It

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The ADSP-218x tools use AEXE as an object file
format. The 7.0 release of theADSP- 218x tools
will be an ELF/DWARF toolset.

The following table shows object and debug formats for ADI tools:

Toolset 3.3

SHARC

Object

COFF ELF ELF AEXE ELF ELF ELF

4.0
SHARC

4.1
SHARC

these users can convert their libraries to ELF and

6.1 218x 7.0 218x 21160 TS001

proceed using the latest tools.

Format
Debug

SDB SDB DWARF NONE DWARF DWARFDWAR

Format
Object file

.obj .doj .doj .obj .doj .doj .doj

extension
Executable

.exe .dxe .dxe .exe .dxe .dxe .dxe

extension

Object File Implications

If you are starting a new program the object file
format and debug information format shouldn't
affect how you program at all. There are the
general advantages of using industry standard file
formats as described towards the end of this note.

When the SHARC 4.0 tools were released, users
were able to convert COFF object files to ELF. In
addition, the VisualDSP debugger in the 4.0 release
was able to read and debug COFF object files
directly (without conversion). Users who had 3.3

generated files that contained debugging information
If you have existing code targeted for a non-ADI
part, the object file format shouldn't affect you
either. You will need to recompile your C code,
translate and assemble any assembly code, and then
proceed.

would find that the object file converter would

preserve the debugging information. This behavior is

unique to the 4.0 SHARC tools (and the 4.0.1

service pack). In general, most object file

converters will not preserve debug information.

F

If you are migrating from previous versions of ADI
tools, you may notice a difference. The
ELF/DWARF object format is richer in information
than the previous object formats. ADI will provide
object file converters (e.g., coff2elf that converts
from SHARC 3.3 COFF format to ELF, or
aexe2elf that converts from 218x AEXE format to
ELF) that will convert existing object files and

A SHARC Example

If you had an object library of math routines that

were in COFF format, you would be able to run the

coff2elf conversion tool over the library to produce

an object library of math routines that were in ELF

format. You could then use the ELF/DWARF

tools for the rest of your development. You would

be able to use the math routines as before.
executables to the ELF/DWARF format.

Converting an Existing Object File with Debug

ADI recommends using the latest tools to rebuild
from source. But in many cases users will have
libraries for which they may not have source code.
Using the object file converters

EE-110 Page 2

Technical Notes on using Analog Devices’ DSP components and development tools

Phone: (800) ANALOG-D, FAX: [phone], EMAIL: [e-mail], FTP: ftp.analog.com,

WEB: www.analog.com/dsp

Information

If you have an existing object file that already

contains debug information you have two choices.

If you have the source you can recompile to