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tool/link.h: remove outdated comment

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Norman Feske 2018-05-21 19:15:41 +02:00 committed by Christian Helmuth
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tool/link.h
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@ -2,39 +2,6 @@
* \brief Stub for compiling GCC support libraries without libc
* \author Norman Feske
* \date 2011-08-31
*
* The target components of GCC tool chains (i.e. libsupc++, libgcc_eh, and
* libstdc++) depend on the presence of libc includes. For this reason, a C
* library for the target platform is normally regarded as a prerequisite for
* building a complete tool chain. However, for low-level operating-system
* code, this prerequisite is not satisfied.
*
* There are two traditional solutions to this problem. The first is to leave
* out those target components from the tool chain and live without full C++
* support (using '-fno-rtti' and '-fno-exceptions'). Because Genode relies on
* such C++ features however, this is no option. The other traditional solution
* is to use a tool chain compiled for a different target platform such as
* Linux. However, this approach calls for subtle problems because the target
* components are compiled against glibc and make certain presumptions about
* the underlying OS environment. E.g., the 'libstdc++' library of a Linux tool
* chain contains references to glibc's 'stderr' symbol, which does not exist
* on Genode's libc derived from FreeBSD. More critical assumptions are related
* to the mechanism used for thread-local storage.
*
* This header file overcomes these problems by providing all function
* prototypes and type declarations that are mandatory for compiling GCC's
* target components. Using this libc stub, all GCC target components can be
* built without the need for additional libc support. Of course, for actually
* using these target components, the target OS has to provide the
* implementation of a small subset of functions declared herein. On Genode,
* this subset is provided by the 'cxx' library.
*
* The code of the target components expects usual C header file names such as
* 'stdio.h'. It does not include 'libgcc_libc_stub.h'. By creating symlinks
* for all those file names pointing to this file, we ensure that this file is
* always included on the first occurrence of the inclusion of any libc header
* file. The set of symlinks pointing to this libc stub are created
* automatically by the 'tool_chain' script.
*/
/*