genode/repos/base/src/lib/ldso
Norman Feske 4f69772ecc Replace 'Env' interface with modern one
The original 'Env' interface as returned by 'Genode::env()' has been
renamed to 'Env_deprecated' and moved to deprecated/env.h. The new version
of base/env.h contains the interface passed to modern components that
use the component API via base/component.h.

Issue #1832
2016-05-09 13:10:52 +02:00
..
include ldso: dump link map of loaded shared objects 2016-04-25 10:48:01 +02:00
spec ldso: Support for RISC-V 2016-02-26 11:36:51 +01:00
startup base: Genode's dynamic linker 2014-11-12 14:44:15 +01:00
debug.cc ldso: dump link map of loaded shared objects 2016-04-25 10:48:01 +02:00
dependency.cc Minor cleanup fixes 2015-08-21 11:00:59 +02:00
exception.cc ldso: Refactor dynamic linker 2015-03-19 08:57:22 +01:00
file.cc Consolidate RM service into PD session 2016-05-09 13:10:51 +02:00
linker.ld base: Genode's dynamic linker 2014-11-12 14:44:15 +01:00
linux-32.ld ldso: Make truly self relocatable 2015-12-10 13:16:25 +01:00
main.cc Replace 'Env' interface with modern one 2016-05-09 13:10:52 +02:00
README base: Genode's dynamic linker 2014-11-12 14:44:15 +01:00
shared_object.cc ldso: dump link map of loaded shared objects 2016-04-25 10:48:01 +02:00
symbol.map ldso: add lx_environ to symbol map 2015-07-07 19:48:07 +02:00
test.cc base: Genode's dynamic linker 2014-11-12 14:44:15 +01:00

This directory contains Genode's dynamic linker (ldso)


Usage
-----

To build a shared library instead of a regular static library, you just need to
declare 'SHARED_LIB = yes' in the library-description file.  When doing so, a
'<libname>.lib.so' file will be generated and installed in the
'<build-dir>/bin/' directory.  For building an executable that uses a shared
library, no special precautions are needed. The build system will automatically
detect the use of shared libraries, concludes that the binary must be
dynamically linked, and will use the correct linker script.  When loading a
dynamically linked program, the dynamic linker 'ldso.lib.so' and all used shared
objects must be loaded as well.

The linker can be configured through the '<config>' node when loading a dynamic
binary. Currently there are to configurations options, 'ld_bind_now="yes"'
causes the linker to resolve all symbol references on program loading.
'ld_verbose="yes"' outputs library load informations before starting the
program.

Configuration snippet:

!<!-- bind immediately, no library informations -->
!<start name="dynamic_binary">
!  <resource name="RAM" quantum="1M" />
!  <config ld_bind_now="yes" ld_verbose="no">
!  </config>
!</start>

Debugging dynamic binaries with GDB stubs
-----------------------------------------

! # go to directory containing the binaries
! cd <build/dir>/bin
!
! # start GDB with binary to debug
! gdb <binary name>
!
! # break in main routine
! b main
!
! # inspect loaded shared libraries
! info sharedlibrary
!
! # load shared symbols of shared libraries (if not already loaded)
! share
!
! # from here you can debug within libraries

:Known issues:

GDB 7.2 has a regression bug in its line information parser. These issue has
been fixed with version 7.3.