On Tue, Jul 30, 2013 at 06:05:00PM +0400, Andrey Ponomarenko wrote:
I created a dump of a library debug-info by the "eu-readelf
--debug-dump=info" command. The formal_parameter of a subprogram has
type "(GNU_ref_alt) [ N]", but N is not described anywhere in the
I have take a look at the source code of elfutils and found, that
DW_FORM_GNU_ref_alt is an offset in the "alternate debuginfo":
DW_FORM_GNU_ref_alt = 0x1f20, /* offset in alternate .debuginfo. */
DW_FORM_GNU_strp_alt = 0x1f21 /* offset in alternate .debug_str. */
How can I read/dump this "alternate debuginfo"?
DWARF extensions elfutils recognizes/supports are described at:
When configured with --enable-dwz libdw will resolve these FORMs.
The new forms are described in this DWARF5 proposal:
You can find the alt dwz file by reading the .gnu_debugaltlink section.
Which contains a file name followed by the build-id of the dwz file.
Resolving the build-id is done in the regular way as described at
The build-id symlink will point at the /usr/lib/debug/.dwz/ file.