To build libdwarf.a, type
./configure
make
To use dwarf or libdwarf, you may want to install dwarf.h and
libdwarf.h somewhere convenient, and you may need the libdwarf
in the accompanying libdwarf directory
Multi Threading, or using threads with libdwarf (Thread Safety):
Nothing in libdwarf does any locking. Every Dwarf_Debug
(such as returned by dwarf_init()) is fully independent
of all other Dwarf_Debug-s. However, calls to libdwarf can
change a Dwarf_Debug. So it is unsafe to have two different
threads accessing a single Dwarf_Debug simultaneously.
It is therefore sufficient to ensure than any one Dwarf_Debug
is only accessed from a single thread.
Warnings like
"warning: cast from pointer to integer of different size"
at compile time are to be expected in dwarf_frame.c and
dwarf_frame2.c. Do not be alarmed.
If your headers are not in the expected places,
use the configure script to access them (and to add other ld
or C flags).
For example
./configure CPPFLAGS="-I/home/davea/inc" CFLAGS="-I/home/davea/inc"
Set both CFLAGS and CPPFLAGS so that configure works properly.
If you are using the old frame interfaces and depend on
the use of DW_FRAME_CFA_COL you must add --enable-oldframecol
to the ./configure options to configure libdwarf.
See NEWS and libdwarf2.1.mm/pdf .
To generate SGI IRIX 64 bit offsets (in the producer code)
configure with --enable-dwarf-format-sgi-irix.
To configure with only 32bit offsets (aka DWARF2) configure
with --enable-dwarf-format-strict-32bit.
By default the producer now generates 32bit offsets by default
but one can turn on DWARF3 64bit offset generation at runtime by ORing
DW_DLC_OFFSET_SIZE_64 onto the flags in the call to
dwarf_producer_init() (or dwarf_producer_init_b) [when the
address size is specified as 64 bit].
Mac OSX (June 2010): Since MacOSX does not use elf, there is no elf.h
header in the headers provided on MacOSX.
Use a search engine (like google) to find an elf.h you can use.
http://www.rockbox.org/tracker/9006?getfile=16683
might be useful.
In addition, the archive (ar) program on MacOSX does not
automatically generate some data so modify the generated
Makefile to add -s to the options to ar.
To enable dection of Windows pathnames as full paths
add --enable-windowspath. Doing this does mean things like
A:foo and \anything are treated as full paths (these are
unlikely path names on a POSIX system but are legal
POSIX partial paths).
It is possible to request a shared library (libdwarf.so) build with
--enable-shared
To turn off the build of the archive library (libdwarf.a) specify
--disable-nonshared
but in this case you must specify --enable-shared or nothing will
build!
TARGET DEPENDENCIES of .debug_frame:
dwarf.h
These should be revised if you have more than the defined
63 'normal' registers. It's not harmful to have these too large!
Too small will lead to errors reading .debug_frame and .eh_frame.
DW_FRAME_HIGHEST_NORMAL_REGISTER
DW_FRAME_LAST_REG_NUM
These you might revise, but can safely ignore if simply
using dwarfdump. If using the producer code you will want
to get these exactly right for your architecture.
DW_FRAME_RA_COL
DW_FRAME_STATIC_LINK
DW_FRAME_CFA_COL
libdwarf.h
The DW_FRAME_REG_INITIAL_VALUE #define should be set to
the value appropriate to your architecture. See libdwarf.h
for details.
If DW_REG_TABLE_SIZE is not set large enough attempts to
fill in the .debug_frame tables will get an error.
Should be at least as large as DW_FRAME_LAST_REG_NUM.
If it's too large nothing is harmed (but some extra space taken
at run time).
If your printf does not support C standard %llx etc,
(such as MSWindows with long long), configure
option --enable-nonstandardprintf
and defines like DW_PR_DUx etc in libdwarf.h
provide a way to configure for that relatively easily.
The .debug_frame is so very architecture dependent
and because the host (where libdwarf/dwarfdump are executed)
and target (the objects read) could be different.
It's currently not supported to have dwarfdump/libdwarf determine
the architecture on-the-fly and do-the-right-thing.
Just setting DW_FRAME_LAST_REG_NUM and DW_FRAME_HIGHEST_NORMAL_REGISTER
and DW_REG_TABLE_SIZE high enough will likely suffice for most
purposes and most compilers/architectures..
See comments in dwarf.h/libdwarf.h.
It's perfectly safe to ignore the above suggestions as long
as libdwarf does not get a DW_DLE_DF_REG_NUM_TOO_HIGH error.
(which would only happen on reading .debug_frame or .eh_frame data).
If you intend to use the libdwarf dwarf-producer code
for .debug_frame information
you must do a thorough analysys and revise dwarf.h
substantially to match the output target architecture.
In general, in the producer code, numbers are copied from and
to integers with memcpy(). In case of endianness problems,
constants set in dwarf_producer_init() can fix the problems.
If one wants to produce a *different-endian* output the best
solution is to change the integer memcpy calls to call thru a
new dbg-based function pointer and have it 'do the right thing'
to adjust endianness. Set the function pointer correctly in
dwarf_producer_init() and the rest of the code will just call
thru the function pointer. Tedious work to find and change the
memcpy calls to be dbg->de_memcpy(), but once done the code is
no longer endian dependent (right now there is no way to ask
for cross-endian: a new flag needed or ?).
leb128 numbers are endian-independent, so nothing need be
done with those for cross-endian support (the storage
of leb128 on disk is always little-endian).
The .ps files are postscript. So those who cannot deal with mm
format files but do have a postscript printer (or have
ghostscript) can print the documents.
This form was chosen before pdf format existed...
libdwarf2.1.ps documents a way for a debugger to read dwarf information.
libdwarf2p.1.ps documents a way for a compiler to generate dwarf information.
dwarf.v2.ps documents Dwarf Version 2.
index.v2.ps is an index to dwarf.v2.ps.
indexDW.v2 is a plain text index of dwarf #defines to dwarf.v2.ps
mips_extensions.ps documents the mips/sgi extensions to dwarf.
The commands used to generate the postscript were:
pr -t -e libdwarf2.1.mm | tbl | psroff -t -mm >libdwarf2.1.ps
pr -t -e libdwarf2p.1.mm | tbl | psroff -t -mm >libdwarf2p.1.ps
pic dwarf.v2.mm | tbl | psroff -t -mm >dwarf.v2.ps 2> newIndex
pic index.v2.mm | tbl | psroff -t -mm >index.v2.ps
pic is a picture processing tool (ATT command).
tbl is a table-processing tool.
(part of Documentor's Work Bench on ATT-like systems).
tbl and pic are available on linux.
psroff is a name for a troff-like processor, part of
Documentor's Work Bench on IRIX. Substitute a
troff-like or nroff-like processor.
The index.v2.mm was generated by the dwarf-document writer
using some local ATT/USL tools (which SGI does not have, so
there is no way I know of to regenerate this).
To use dwarf or libdwarf, you may want to install dwarf.h and
libdwarf.h somewhere convenient.
You will also need libelf (libelf.a and/or libelf.so) and
libelf.h installed. These are available from GNU repositories.
$Source: /home/davea/dwarf/dwarf-working/trunk/libdwarf/README,v $
$Revision: 1.1 $
$Date: 2009/11/23 17:15:37 $
