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cb43e04691
Ldso now does not automatically execute static constructors of the binary and shared libraries the binary depends on. If static construction is required (e.g., if a shared library with constructor is used or a compilation unit contains global statics) the component needs to execute the constructors explicitly in Component::construct() via Genode::Env::exec_static_constructors(). In the case of libc components this is done by the libc startup code (i.e., the Component::construct() implementation in the libc). The loading of shared objects at runtime is not affected by this change and constructors of those objects are executed immediately. Fixes #2332
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.