genode

History

Josef Söntgen 2490e399dc ldso: check binary pointer before lookup Check if the binary pointer is valid before attempting to lookup the symbol. Shared objects with unresolved symbols and missing depencies, e.g a library that references 'errno' but is not linked against libc, will now produce an error message when they are loaded by the dynamic linker. Fixes #1904.		2016-03-08 17:07:36 +01:00
..
include	ldso: Support for RISC-V	2016-02-26 11:36:51 +01:00
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
README	base: Genode's dynamic linker	2014-11-12 14:44:15 +01:00
debug.cc	ldso: Refactor dynamic linker	2015-03-19 08:57:22 +01:00
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	Minor cleanup fixes	2015-08-21 11:00:59 +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	ldso: check binary pointer before lookup	2016-03-08 17:07:36 +01:00
shared_object.cc	ldso: Refactor dynamic linker	2015-03-19 08:57:22 +01:00
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

README

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.